V-Jet
05-30-2004, 01:09 PM
Okay, a few guys have asked me for feedback on this conversion, so I thought I'll do a write up here instead.
First of all, a brief history and description of Electronic Climate Control, or ECC. It was first introduced as standard equipment on the face-lift 760's from 1988, as well as 780's of the same year. From 1990 ECC was offered as an option on 740's, and it was also available as option on 940 right from the start in 1991, although I've never seen a 740 or 940 in US / Canada with ECC, so I believe it wasn't available for these models in North America. All the early 960’s up to 1994 had ECC as standard, although an interesting version of ECC without aircon appeared on European 960’s from 1993 as another option. From 1995 the European 960 was also available with standard aircon or even basic heating without aircon, the ECC without aircon option was dropped at the same time. But in US / Canada, all the 960’s had ECC with aircon as standard equipment.
The most important component of the ECC is the control panel itself, which is literally a small computer receiving inputs from 3 temperature sensors (ambient temp. sensor near the blower fan, engine temp. sensor near the heater matrix, interior temp. sensor hidden in the dome light), and a solar sensor on the dash. The control panel sends output signal to the servomotor which open & closes the hot air mixer shutter, solenoid valve to redirect vacuum for opening & closing the airflow shutters, and the fan which controls fan speed, via a power stage which amplifies the signal. The control panel of ECC has 3 rotary dials, the left dial for fan speed (AUTO, then 0 to 5), middle dial for function (AUTO, or panel vents, floor, bi-level, defrost, and defrost / floor), the right dial is for setting the desired temperature, either in Celsius or Fahrenheit depending on the market. Just a small note here, the earlier version of climate control available on 760's up to 1987 is called Automatic Climate Control or ACC; it has a thumb-dial for temperature selection and a single sliding bar for function & mode selection. ACC is totally different to ECC in its design and functions.
So anyway, onto my conversion... I think it must've been over a year from when the idea was first conceived. I started studying wiring diagram books and parts diagram on VADIS to see if it can be done, how much work is involved and what needs to be changed or added. I then started collecting parts for the conversion, which is why it took so long. I used mainly used parts, because new parts from Volvo is just WAY to expensive (I believe ECC control panel alone is about $1000). The control panel is probably hardest to find, since the ones for 740 / 940 has the face plate angled to suit the dash on these models, so you couldn't just get them off a 760, 780 or 960 because they won’t fit. As I mentioned before, ECC wasn't offered on 740 / 940 at all in US / Canada. Here in Australia they were, but they are still pretty rare, and I ended up getting my control panel off eBay from Germany. Solenoid valve and servomotors are a lot easier to find, because they are interchangeable between different models. In the case of servomotors, they are also fitted to 940's with standard aircon. I got the wiring and power stage off a wrecked 780 from USA. The two temperature sensors on the blower housing and near the heater matrix weren't too expensive so I got them new from Volvo dealer, but the interior temp. sensor and solar sensor cost a lot more so I got them used. Blower fan on my 1990 model is the same, so I just used my existing blower fan. On the earlier models up to 1989 they are different, they have a single pin connector, but Volvo doesn't sell the earlier type anymore, if you go to a Volvo dealer you will get the later 2-pin connector type. The earlier blower motor housing needs to be modified to fit the later fan, which Volvo published instructions for in their 700 series climate control service book.
I started the conversion by taking the dashboard off, that took me about a day. Everything on the dash, including instrument cluster, radio, old A/C control panel... etc has to go. Once the dash is off, I started removing as much wiring associated with the old standard aircon as I could. Most wiring came to a few connectors around the centre console, which made removal of the old harness and fitting of the new harness a lot easier. I only had to splice 3 wires from the old wiring loom, one for the A/C pressure switch, the other two for auxiliary electric fan relay. In the end all the wires match up! I didn't have to run any wires through the firewall. But I strongly recommend having two copies of the wiring diagram, one for your car and the other for the car which you pulled the wiring from. In my case I was fitting ECC wiring from a 780 into my 740, and the wires have different colour coding! Fortunately I have a copy of both 740 as well as 780 wiring diagram in front of me, so I could cross-reference and know which wire corresponds to which. Apart from fitting the wiring inside the car, the only other alteration to the A/C wiring is that you need to bypass the pressure sensor on the A/C piping which switch on the auxiliary cooling fan, on models with ECC the cooling fan is switched on directly by the ECC control panel instead. For both ECC and standard aircon, the auxiliary cooling fan is also switched on by a temperature sensor in the radiator. (NOTE : This only applies to models with mechanical engine fan and front mounted auxiliary electric cooling fan. From 1992 models onwards both fans are replaced by a single large electric cooling fan behind the radiator. I am not certain how Volvo wired that up with ECC, you’ll need to do more research if your car has the single electric fan arrangement).
Another note here on the wiring - the dome light needs to be changed to one that allows you to fit the interior temp. sensor on the inside. The dome light for ECC has the two front reading lights angled at driver & front passenger, and a hole between the reading lights which is where the temp. sensor is mounted. Physically this dome light fits the existing dome light spot in the roof, although it use a different wiring connector. It’s the same type of 4-pin connector as the rear of the speedometer for late 740's and early 940’s so they’re not hard to find. This type of dome light can be found in all 760, 780 and 960's which are ECC equipped. You will also need to run two wires and the connector to the dome light for the interior temp. sensor, as well as a vacuum hose which connects to the intake manifold via its own one-way valve, separate to the vacuum for the climate control system. The vacuum hose is not essential but the original design is that it draws air over the interior temp. sensor so that it picks up any changes in temperature sooner.
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDEzNDM1NnM0MTNkZmQzMXk1NDE%3D.jpg
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDEzNDM2NnM0MTNkZmQzMXk1NDE%3D.jpg
This was psychologically the worst part of the conversion... I was looking at that mess and thinking to myself "Oh my god, what have I done??? :eek: How am I going to put that all back?"
After I did the wiring, I pulled the blower fan housing out for modification. I've got the later 2-pin type blower fan already, but I still need to modify the housing to fit the power stage and ambient temp. sensor. Speaking of the blower fan housing, WHOEVER DESIGNED THE BLOWER FAN HOUSING ON 740 / 940 NEEDS TO BE SHOT!!! I cracked my blower fan housing as I was taking it out, right at the evaporator drain spout. And Volvo wanted a fortune for that blower fan housing!!! I ended up buying a whole climate control box from my local Volvo salvage yard, without the evaporator, for less than half of what Volvo wants just for a blower fan housing!!! I mentioned this to my mechanic in a conversation, he said it's very common, he's cracked a few himself while taking the housing off to replace evaporators in 740 / 940's, right at the drain spout too. To modify for the power stage, I started from the resistor pack mounting location for standard aircon, and basically enlarged it until the power stage can fit in there. A mini hacksaw comes in very handy here! :-D I drilled then cut on the opposite side of the power stage, the side closer to the firewall, for the mounting location of the ambient temp. sensor.
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDE0NjU5NnM0MTNkZmQzMXk1NDE%3D.jpg
Modified blower fan housing, ready to be installed. The thing in the foreground with lots of fins on it is the power stage. Notice on the opposite side I have also drilled for the ambient temp. sensor. I followed how Volvo factory installed ECC on 740 / 940 as closely as possible.
The engine temp. sensor measures coolant temperature near the heater matrix, and it's mounted just behind the two vacuum motors on the airflow box, which directs the airflow. I initially wanted to drill for this in the car, but then I realised that sitting very closely behind it is the heater matrix, and if my drill went too far and I put a hole in that too I'll REALLY be having fun!! To take the airflow box out, first you need to remove the two floor ducts which directs air to the feet for rear passengers, then slide the floor duct box out (held in by 1 screw) from under the airflow box, which reveals access to a few bolts that you need to remove. A few vacuum hoses needs to be disconnected too but that's pretty straightforward. Drilling on the airflow box is a little bit easier as the mounting location is already pre-marked. Not sure if all models have the mounting location pre-marked or only on 1990+ models, the climate control box from a 1991 940 which I bought to replace my cracked blower fan housing also had this pre-marked. Removing the airflow box turned out to be a wise step as it gave me easier access to the next step of the conversion, and also allowed me to thoroughly clean out all the yucky, sticky, deteriorating black foam. A lot of it blew out through the vents a few years ago, but I vacuumed off what's left on there to make sure I'll never see it again :twisted:
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDE0NjYwNnM0MTNkZmQzMXk1NDE%3D.jpg
Engine temp. sensor mounting hole on the airflow box, drilled and ready to be re-installed.
The next step was fitting the servomotor and solenoid valve. Servomotor opens and closes the hot air mixer shutter, while solenoid valve redirects the vacuum which controls the airflow. If your doing this conversion on a 940, or a '91+ 740 then you can forget about adding the servomotor, because you've got it already! From 1991 the 740 and 940 received a minor update on the standard aircon which use the same servomotor as for the ECC to control the hot air mixer shutter. On my 1990 model however (and older models too), the hot air mixer shutter is operated by a cable connected to the old standard aircon control panel, so you need to remove the cable, as well as the old control arm, then install a new control arm with a metal connecting rod to the servomotor. Pulling the old control arm out turned out to be quite difficult, because it was quite stubborn and you don't have a lot of room to work with. Both the servomotor and solenoid valve are fitted onto a metal plate, which is pop-riveted to the side of the climate control box. I drilled on the box then pop-riveted the metal plates in place. Since I removed the airflow box for drilling the engine temp. sensor. I could easily reach behind the area where I drilled, and I used metal washers on the other side for extra support when I pop-riveted those brackets in. I could also easily vacuum out the plastic shreds from drilling the holes.
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDE0NjYxNnM0MTNkZmQzMXk1NDE%3D.jpg
Immediately to the right of the vacuum tank, you can see the servomotor on top of the solenoid valve. Notice the blower housing and airflow box is still removed.
Once that's done, you can start putting the blower fan housing and airflow box back in place, in preparation for the dash re-assembly. But first you need to fill the edge of both with sealant before you put it back, to make sure it doesn't leak air. And here I need to rant again... I HATE BUTYL!!!! WITH A PASSION!!! :rant: Its black and sticky, looks so disgusting, and it gets everywhere, especially when getting that blower fan housing back in. I don't know how many times I've washed my hands and my arms, as well as taking showers, but I still have bits of butyl on my arm right now. I also got it all over my Burberry shirt, it better come off with something or else I'm gonna be even more pissed off!!!
Before you put the dash back, if you're doing this conversion on a 1990 or earlier 740 then you also need to drill for solar sensor mounting. On the 1990 models, a mounting location is pre-drilled on the metal frame of the dash, on the passenger side between the defroster vents and the A pillar, although it's covered up by foam. But it does make drilling a lot easier because you're only drilling through foam, not metal. I'm not sure if the earlier 740's have this mounting location pre-drilled, I have a feeling that they're not because ECC wasn't available on 740's until 1990. On the 940's and 1991+ 740's however, the solar sensor is mounted on the passenger side dash speaker grille, so you don't need to drill the dash, just drill or change the speaker grille.
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDEzNTAyNnM0MTNkZmQzMXk1NDE%3D.jpg
My dash re-installed, as well as the ECC control panel.
So far I haven't fully completed the conversion, as I haven't attached the vacuum hoses to the solenoid valve yet. I plan to drill out the vacuum hoses on the old vacuum hose harness attachment, then glue in my existing vacuum hoses before plugging it back in. I can't conform that it's working, but I can hear the solenoid valve clicking when I change functions, and the built-in self diagnostic feature of the ECC hasn't picked up any system errors, so I'm assuming that it works. I also haven't ran the wiring and vacuum hose to the dome light for the interior temp. sensor. I will be doing both shortly and post updates when it's done.
First of all, a brief history and description of Electronic Climate Control, or ECC. It was first introduced as standard equipment on the face-lift 760's from 1988, as well as 780's of the same year. From 1990 ECC was offered as an option on 740's, and it was also available as option on 940 right from the start in 1991, although I've never seen a 740 or 940 in US / Canada with ECC, so I believe it wasn't available for these models in North America. All the early 960’s up to 1994 had ECC as standard, although an interesting version of ECC without aircon appeared on European 960’s from 1993 as another option. From 1995 the European 960 was also available with standard aircon or even basic heating without aircon, the ECC without aircon option was dropped at the same time. But in US / Canada, all the 960’s had ECC with aircon as standard equipment.
The most important component of the ECC is the control panel itself, which is literally a small computer receiving inputs from 3 temperature sensors (ambient temp. sensor near the blower fan, engine temp. sensor near the heater matrix, interior temp. sensor hidden in the dome light), and a solar sensor on the dash. The control panel sends output signal to the servomotor which open & closes the hot air mixer shutter, solenoid valve to redirect vacuum for opening & closing the airflow shutters, and the fan which controls fan speed, via a power stage which amplifies the signal. The control panel of ECC has 3 rotary dials, the left dial for fan speed (AUTO, then 0 to 5), middle dial for function (AUTO, or panel vents, floor, bi-level, defrost, and defrost / floor), the right dial is for setting the desired temperature, either in Celsius or Fahrenheit depending on the market. Just a small note here, the earlier version of climate control available on 760's up to 1987 is called Automatic Climate Control or ACC; it has a thumb-dial for temperature selection and a single sliding bar for function & mode selection. ACC is totally different to ECC in its design and functions.
So anyway, onto my conversion... I think it must've been over a year from when the idea was first conceived. I started studying wiring diagram books and parts diagram on VADIS to see if it can be done, how much work is involved and what needs to be changed or added. I then started collecting parts for the conversion, which is why it took so long. I used mainly used parts, because new parts from Volvo is just WAY to expensive (I believe ECC control panel alone is about $1000). The control panel is probably hardest to find, since the ones for 740 / 940 has the face plate angled to suit the dash on these models, so you couldn't just get them off a 760, 780 or 960 because they won’t fit. As I mentioned before, ECC wasn't offered on 740 / 940 at all in US / Canada. Here in Australia they were, but they are still pretty rare, and I ended up getting my control panel off eBay from Germany. Solenoid valve and servomotors are a lot easier to find, because they are interchangeable between different models. In the case of servomotors, they are also fitted to 940's with standard aircon. I got the wiring and power stage off a wrecked 780 from USA. The two temperature sensors on the blower housing and near the heater matrix weren't too expensive so I got them new from Volvo dealer, but the interior temp. sensor and solar sensor cost a lot more so I got them used. Blower fan on my 1990 model is the same, so I just used my existing blower fan. On the earlier models up to 1989 they are different, they have a single pin connector, but Volvo doesn't sell the earlier type anymore, if you go to a Volvo dealer you will get the later 2-pin connector type. The earlier blower motor housing needs to be modified to fit the later fan, which Volvo published instructions for in their 700 series climate control service book.
I started the conversion by taking the dashboard off, that took me about a day. Everything on the dash, including instrument cluster, radio, old A/C control panel... etc has to go. Once the dash is off, I started removing as much wiring associated with the old standard aircon as I could. Most wiring came to a few connectors around the centre console, which made removal of the old harness and fitting of the new harness a lot easier. I only had to splice 3 wires from the old wiring loom, one for the A/C pressure switch, the other two for auxiliary electric fan relay. In the end all the wires match up! I didn't have to run any wires through the firewall. But I strongly recommend having two copies of the wiring diagram, one for your car and the other for the car which you pulled the wiring from. In my case I was fitting ECC wiring from a 780 into my 740, and the wires have different colour coding! Fortunately I have a copy of both 740 as well as 780 wiring diagram in front of me, so I could cross-reference and know which wire corresponds to which. Apart from fitting the wiring inside the car, the only other alteration to the A/C wiring is that you need to bypass the pressure sensor on the A/C piping which switch on the auxiliary cooling fan, on models with ECC the cooling fan is switched on directly by the ECC control panel instead. For both ECC and standard aircon, the auxiliary cooling fan is also switched on by a temperature sensor in the radiator. (NOTE : This only applies to models with mechanical engine fan and front mounted auxiliary electric cooling fan. From 1992 models onwards both fans are replaced by a single large electric cooling fan behind the radiator. I am not certain how Volvo wired that up with ECC, you’ll need to do more research if your car has the single electric fan arrangement).
Another note here on the wiring - the dome light needs to be changed to one that allows you to fit the interior temp. sensor on the inside. The dome light for ECC has the two front reading lights angled at driver & front passenger, and a hole between the reading lights which is where the temp. sensor is mounted. Physically this dome light fits the existing dome light spot in the roof, although it use a different wiring connector. It’s the same type of 4-pin connector as the rear of the speedometer for late 740's and early 940’s so they’re not hard to find. This type of dome light can be found in all 760, 780 and 960's which are ECC equipped. You will also need to run two wires and the connector to the dome light for the interior temp. sensor, as well as a vacuum hose which connects to the intake manifold via its own one-way valve, separate to the vacuum for the climate control system. The vacuum hose is not essential but the original design is that it draws air over the interior temp. sensor so that it picks up any changes in temperature sooner.
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDEzNDM1NnM0MTNkZmQzMXk1NDE%3D.jpg
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDEzNDM2NnM0MTNkZmQzMXk1NDE%3D.jpg
This was psychologically the worst part of the conversion... I was looking at that mess and thinking to myself "Oh my god, what have I done??? :eek: How am I going to put that all back?"
After I did the wiring, I pulled the blower fan housing out for modification. I've got the later 2-pin type blower fan already, but I still need to modify the housing to fit the power stage and ambient temp. sensor. Speaking of the blower fan housing, WHOEVER DESIGNED THE BLOWER FAN HOUSING ON 740 / 940 NEEDS TO BE SHOT!!! I cracked my blower fan housing as I was taking it out, right at the evaporator drain spout. And Volvo wanted a fortune for that blower fan housing!!! I ended up buying a whole climate control box from my local Volvo salvage yard, without the evaporator, for less than half of what Volvo wants just for a blower fan housing!!! I mentioned this to my mechanic in a conversation, he said it's very common, he's cracked a few himself while taking the housing off to replace evaporators in 740 / 940's, right at the drain spout too. To modify for the power stage, I started from the resistor pack mounting location for standard aircon, and basically enlarged it until the power stage can fit in there. A mini hacksaw comes in very handy here! :-D I drilled then cut on the opposite side of the power stage, the side closer to the firewall, for the mounting location of the ambient temp. sensor.
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDE0NjU5NnM0MTNkZmQzMXk1NDE%3D.jpg
Modified blower fan housing, ready to be installed. The thing in the foreground with lots of fins on it is the power stage. Notice on the opposite side I have also drilled for the ambient temp. sensor. I followed how Volvo factory installed ECC on 740 / 940 as closely as possible.
The engine temp. sensor measures coolant temperature near the heater matrix, and it's mounted just behind the two vacuum motors on the airflow box, which directs the airflow. I initially wanted to drill for this in the car, but then I realised that sitting very closely behind it is the heater matrix, and if my drill went too far and I put a hole in that too I'll REALLY be having fun!! To take the airflow box out, first you need to remove the two floor ducts which directs air to the feet for rear passengers, then slide the floor duct box out (held in by 1 screw) from under the airflow box, which reveals access to a few bolts that you need to remove. A few vacuum hoses needs to be disconnected too but that's pretty straightforward. Drilling on the airflow box is a little bit easier as the mounting location is already pre-marked. Not sure if all models have the mounting location pre-marked or only on 1990+ models, the climate control box from a 1991 940 which I bought to replace my cracked blower fan housing also had this pre-marked. Removing the airflow box turned out to be a wise step as it gave me easier access to the next step of the conversion, and also allowed me to thoroughly clean out all the yucky, sticky, deteriorating black foam. A lot of it blew out through the vents a few years ago, but I vacuumed off what's left on there to make sure I'll never see it again :twisted:
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDE0NjYwNnM0MTNkZmQzMXk1NDE%3D.jpg
Engine temp. sensor mounting hole on the airflow box, drilled and ready to be re-installed.
The next step was fitting the servomotor and solenoid valve. Servomotor opens and closes the hot air mixer shutter, while solenoid valve redirects the vacuum which controls the airflow. If your doing this conversion on a 940, or a '91+ 740 then you can forget about adding the servomotor, because you've got it already! From 1991 the 740 and 940 received a minor update on the standard aircon which use the same servomotor as for the ECC to control the hot air mixer shutter. On my 1990 model however (and older models too), the hot air mixer shutter is operated by a cable connected to the old standard aircon control panel, so you need to remove the cable, as well as the old control arm, then install a new control arm with a metal connecting rod to the servomotor. Pulling the old control arm out turned out to be quite difficult, because it was quite stubborn and you don't have a lot of room to work with. Both the servomotor and solenoid valve are fitted onto a metal plate, which is pop-riveted to the side of the climate control box. I drilled on the box then pop-riveted the metal plates in place. Since I removed the airflow box for drilling the engine temp. sensor. I could easily reach behind the area where I drilled, and I used metal washers on the other side for extra support when I pop-riveted those brackets in. I could also easily vacuum out the plastic shreds from drilling the holes.
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDE0NjYxNnM0MTNkZmQzMXk1NDE%3D.jpg
Immediately to the right of the vacuum tank, you can see the servomotor on top of the solenoid valve. Notice the blower housing and airflow box is still removed.
Once that's done, you can start putting the blower fan housing and airflow box back in place, in preparation for the dash re-assembly. But first you need to fill the edge of both with sealant before you put it back, to make sure it doesn't leak air. And here I need to rant again... I HATE BUTYL!!!! WITH A PASSION!!! :rant: Its black and sticky, looks so disgusting, and it gets everywhere, especially when getting that blower fan housing back in. I don't know how many times I've washed my hands and my arms, as well as taking showers, but I still have bits of butyl on my arm right now. I also got it all over my Burberry shirt, it better come off with something or else I'm gonna be even more pissed off!!!
Before you put the dash back, if you're doing this conversion on a 1990 or earlier 740 then you also need to drill for solar sensor mounting. On the 1990 models, a mounting location is pre-drilled on the metal frame of the dash, on the passenger side between the defroster vents and the A pillar, although it's covered up by foam. But it does make drilling a lot easier because you're only drilling through foam, not metal. I'm not sure if the earlier 740's have this mounting location pre-drilled, I have a feeling that they're not because ECC wasn't available on 740's until 1990. On the 940's and 1991+ 740's however, the solar sensor is mounted on the passenger side dash speaker grille, so you don't need to drill the dash, just drill or change the speaker grille.
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDEzNTAyNnM0MTNkZmQzMXk1NDE%3D.jpg
My dash re-installed, as well as the ECC control panel.
So far I haven't fully completed the conversion, as I haven't attached the vacuum hoses to the solenoid valve yet. I plan to drill out the vacuum hoses on the old vacuum hose harness attachment, then glue in my existing vacuum hoses before plugging it back in. I can't conform that it's working, but I can hear the solenoid valve clicking when I change functions, and the built-in self diagnostic feature of the ECC hasn't picked up any system errors, so I'm assuming that it works. I also haven't ran the wiring and vacuum hose to the dome light for the interior temp. sensor. I will be doing both shortly and post updates when it's done.