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Old 04-01-2012, 08:52 AM   #1
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Default Volvo's That Run Chapter 20 - AC and Heating

Chapter 20 – Air Conditioning

The Volvo air conditioning system, at least mine in 5 cars, was always marginal. Perhaps the fact that I live in Georgia and 3 of the 5 were wagons may have contributed to that issue. Restoring a 30 year old system to be the best it can be is going to take some time, effort and money. While the AC system did work when the engine quit 17 years ago it didn’t seem to make sense to attempt to reuse the old hoses especially since the connectors were rusty. In fact, one connection to the condenser was so corroded that despite my best efforts the condenser could not be saved.

The complete engine came with the AC compressor and I asked for the associated manifold and hoses but, as it turned out, they were not used. The original AC manifold pressure side tube exited the block directly toward the exhaust header and there was not room to even install a 90 degree compression fitting. Never mind that the pressure sensor didn’t fit either. I found a couple of universal Ford type manifolds that came straight out toward the rear or straight up. Either would have worked but they were over $60 just for the block. That would have made a very nice place to install the high/low charge port fittings but, no . . . .

Instead, I rummaged around a salvage yard and found an ’87 Ford F150 manifold that appeared it would work for $10. When all the smoke cleared I really did not save much because of the other fittings required to make it work. Had I to do it over I would use the ‘out the top’ configuration and a couple 90 degree fittings which would have moved the hoses away from the exhaust headers by a couple inches and made the finished configuration much neater.

’87 Ford F150 AC Manifold

The low pressure side still didn’t fit as it turned just enough to end up pointing at the strut tower without room for a hose coupling. That required the tube be cut and a compression fitting used. I really do not like to use compression fittings on AC systems but it was that or go for the new manifold which had ‘O’ ring connectors.

Test Fitting

Finished Connections

Charging the compressor with oil required, or at least I chose to, remove it from the engine to drain the old oil and pour in the new. The system takes 8 or 9 ounces of PAG 46 oil according to two separate specifications sheets I found. Since the oil comes in 8 oz containers and I am sure that not all drained out that was all it got. I was advised by one of my many contacts asking question to pour it into the suction port and wiggle the shaft to distribute the oil on the seals and lay the compressor on its hub for several minutes before spinning the pump and reinstalling. This compressor had not turned in 12 years so that sounded like reasonable advice. Another reason to remove the compressor. One comment from an AC web site is to tighten the four bolts as you would head bolts, a little at a time so as to not torque the compressor. Also, don’t try to put any oil in the pressure side as it will just blow it back out.

I took the Volvo hoses to the local NAPA store and they made up new ones using new connectors and lengths modified slightly to meet the new connection length requirements. Don’t try to add a few inches ‘just in case’ as the hose is very stiff and too much hose is about as bad as not enough. All new connectors, except for the large one on the suction side of the evaporator core, were used. That large one was not available anywhere that I found so I cut it off the old hose and cleaned it up with a wire brush in an air driven cut-off tool. It too was corroded but cleaned up nicely.

I purchased a set of ‘O’ rings for the Ford system but that proved unnecessary as all the new fitting came with them. Be sure to use the compressor oil to lubricate the ‘O’ rings and threads when assembling the hoses.

Of course you will need to add charge ports on both the pressure and suction sides of the compressor. I installed them at the input to the condenser and at the firewall where the low side hose runs. This is another reason to use a new universal manifold as there are fitting available that would have made installation at the rear of the compressor easy, even less expensive and neater. Anyway, my configuration will work and it is installed.

The receiver/dryer should, of course, be replaced as it should be anytime you open up a system. Especially since mine was 30 years old and had been open for a number of years. It is readily available new and surprisingly inexpensive. It came with a built in pressure blow-out valve so the Ford’s location on the manifold was not needed. Leave the sealed caps on until you are ready to connect the hoses and charge the system.

The new dryer also had the pressure cut out switch used by the Volvo which I spliced into the Ford compressor clutch wiring. The end result is that the original interior Volvo AC controls manage the Ford magnetic clutch through the pressure cut out switch.

I also replaced the expansion valve with one designed for R134a. It’s a good thing that I did not attempt to reuse the old valve as after only 13 year of service it was so clogged up that it would seem impossible to have worked. Maybe that is why I remember it being slightly less than adequate during the Georgia Summers.

In order to remove the valve you have to cut/pull/tear all the black, sticky insulating tape off. The tape must be replaced or you will end up with condensation all over the carpet. It is available at NAPA for about $25 for about 6 times as much as you need. You might try at a local AC repair shop to see if they will sell you enough to cover up the system. In my rural mountains we do not have a AC repair shop so I bought the box.

Blow out the evaporator core to get all the old oil and other crap out. About a tablespoon of oil came out so be prepared with an old towel to cover and catch it.

I tried to educate myself on how to deal with a used condenser. I was unsure whether it had been used for R12 or R134a and what kind of oil was in it so I blew it out and flushed it. There is a product sold specifically for this purpose at about $30 a quart. Half the AC forums I researched said to use brake cleaner, half said not to use brake cleaner. So I cast my vote, went with the majority, and used a $2 can of brake cleaner. Sprayed the entire can into the condenser and with the in and out ports sealed rocked it for a few minutes to circulate the fluid throughout the tubing. When blowing it out with air into a towel did not find a great deal of junk coming out and only a little oil. Left the air blowing through the tubing for a few minutes to get as much of the cleaner out as possible. Make an effort not to breath while doing all this as that stuff cannot be good for your lungs.

The AC system is sealed up at the moment but I am not going to pull a vacuum and charge it until I am reasonably sure that the engine runs and I am not going to have to do something drastic that would affect it.

I’ll come back and provide the ‘rest of the story’ after I get the engine running.

While I have added lots of cans of Freon in my life, especially when R12 was $0.99, and even rebuilt a compressor, I make no claim to knowing even the minimum about safely installing and charging an auto AC system.

Here is the layout and parts list from one of the Green Books so I can get part names correct in this discussion.

Hot Coolant Cut-Off Valve

A suggestion related to many vehicles over decades before everyone went to computer controlled hot/cold air blend technology is to install a valve in the supply line to the heater core to completely cut off hot water circulation during air conditioning season. The Volvo thermo controlled water valve was always iffy as to fully cutting off the hot coolant and the Volvo AC system was always marginal, especially with the extra interior space of the wagon. Coupled with the conversion to R134 coolant which is about 10% less efficient than the R12 originally used in the 240 cars a valve installed in the supply hose to the heater core is a good investment. There are many ones to choose from for a 5/8” hose available in hardware and auto parts stores. I found a plastic version at NAPA that was compact and easy to install ($18).

The parent document to this thread can be found here: http://forums.turbobricks.com/showthread.php?t=250257

Last edited by TestPoint; 04-30-2014 at 06:23 PM..
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Old 04-28-2014, 05:36 PM   #2
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Last Fall I charged up the system with a couple cans of R134 just before one of the coldest winters in memory. It is difficult to anywhere near correctly charge an AC system in cold weather without one of the charge/recovery systems that facilitate charging by weight rather than pressure. Since a large part of my AC experience used $0.99 R12, occasionally on sale for $0.89, and you knew the system was charged when there were no longer bubbles in the sight glass I put it down until an 80 degree day . . . like last Friday.

The static pressure was right where I left it at about 30 psi. Equipped with my professional quality Harbor Freight gauge set I added another half can and got the running pressure up to 30 psi low, 165 psi high with outside temperature in the high seventies. Just about where my cheat sheet said it should be.

The plan is to test for a few days before wrapping the expansion valve with the sticky tape that is there to reduce condensation.

With that I have now officially declared the conversion complete and celebrate with a well deserved bump to the top of the article thread list.

Last edited by TestPoint; 04-30-2014 at 06:16 PM..
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Old 04-30-2014, 02:49 PM   #3
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Don't recall seeing this chapter. Nicely done.
80 Bertone (part-time driver) learn how to 5.0-Volvo here.... http://forums.turbobricks.com/showthread.php?t=250257
B20 sound! https://www.youtube.com/watch?v=6FpMWALskko
242, https://forums.turbobricks.com/showthread.php?t=344891

Last edited by NONHOG; 05-02-2014 at 06:52 PM..
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