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240 AC pressure switch bypassed

volvowagoon

Active member
Joined
Jul 19, 2012
Location
Franklin, IN
Hi all,

My girlfriend just bought an 89 245 with OKAY air conditioning. Put it this way, she preferred to drive it back to Indy from Chicago in 95 degree heat and lot of humidity with the windows up, but still broke a sweat.

I'm well aware that the factory system is less than stellar, and I don't want to ruin a good thing. However, there are some issues that worry me. It was supposedly converted to r134a, but it's still sporting an old receiver/drier up by the core support with the pressure switch bypassed.

I'm new to this particular AC system, but I'm worried that this lack of switch operation might burn up the compressor. After reading this nice article, https://www.240turbo.com/classicair.html I'm wondering if it is possible that it just need an r134a pressure switch that trips at a lower temp. While I have the system evacuated I might try to upgrade the condenser, since that seems like a fairly easy performance upgrade that doesn't require pulling the dash out.

Does replacing this switch sound like a good safety? If so does anybody know where I can get one? Thank you!
 
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For the record... I have yet to hook gauges up to the system to see if the pressures are actually good or not. It might just be a leaky system.
 
Plug the low pressure switch spade connectors back into the connector, then evacuate, vacuum, and recharge the system with ~80% of the original r12 weight (if using r134a).

Don’t get your hopes up, like you said the old systems are weak.
 
Plug the low pressure switch spade connectors back into the connector, then evacuate, vacuum, and recharge the system with ~80% of the original r12 weight (if using r134a).

Don’t get your hopes up, like you said the old systems are weak.

Oh I know. We're pretty content with the performance. I'm mainly just trying to prevent trashing the whole system because of a silly bypass. If I can subtract a few degrees with small upgrades while it's open I figured that would be a nice bonus. Are the thermal expansion valves something that should be replaced every time you open it up like an orifice tube? I've always assumed not.
 
I would recommend to put some gauges on it. If its just low; I would top it off with some R12. You can still buy it on ebay and craigslist. I would not put R134a in it. IF you live in high heat and humidity. I completely went thru my Ac system on my 90 240. I upgraded the condensor and replaced hoses then filled it up with Duracool. It will blow 42 on 98 degree day.
Which when system was on 134a with same upgrades etc. The coldest it would blow was 55 degrees. Alot of people are scared of duracool. Ive researched enough and talked to enough professionals that Im confident that I wont have any problems. Anyway hope this helps you.
 
I would recommend to put some gauges on it. If its just low; I would top it off with some R12. You can still buy it on ebay and craigslist. I would not put R134a in it. IF you live in high heat and humidity. I completely went thru my Ac system on my 90 240. I upgraded the condensor and replaced hoses then filled it up with Duracool. It will blow 42 on 98 degree day.
Which when system was on 134a with same upgrades etc. The coldest it would blow was 55 degrees. Alot of people are scared of duracool. Ive researched enough and talked to enough professionals that Im confident that I wont have any problems. Anyway hope this helps you.

I have a nice brand new gauge set from the MAC truck, and I've been looking for an excuse to use them. My worry about just adding refrigerant is compatibility with whatever is in there. If this car was in fact converted with PAG oil then the r12 wouldn't play too nicely. I would hope that they used ester to avoid that sort of complication and judging by the stock looking parts on the car I doubt they did anything fancy. Either way I'd feel more comfortable flushing everything out and starting over. I bought a kit to do that last night.

Is there any easy way to search for the upgraded condenser? I've heard that the 91+ is the way to go, but there's a little bit of custom work involved in fitting the TXV back on?
 
I think you said that the system has been converted to R134a.

To confirm, are the low and high pressure valves the larger R134a snap on connectors?

Have you measured gas pressure with your new gauge set?

What do you read as static pressure?
 
I think you said that the system has been converted to R134a.

To confirm, are the low and high pressure valves the larger R134a snap on connectors?

Have you measured gas pressure with your new gauge set?

What do you read as static pressure?

I do not see conversion fittings on it, and I have not hooked up the gauges yet either. I was a bit busy with one of the other cars. I gave the 240 a more thorough inspection now that it's home and I revealed some far uglier things. The timing belt is shot, the brake fluid looks like coffee, and the front cam seal is confirmed bad. At least the power steering is full... of brake fluid??? :???:
 
My son achieved acceptable results with his (my old) 89 245.

China copy of condenser @ $100 to the door.
Sanden replacement compressor, bolt in.
Upgraded TXV under dash and possibly a tube or two to enable the conversion (there was a factory kit made to make these machines R134a friendly).
ESTER oil, not PAG for machines which were factory R12 and then converted.
New drier/receiver and new high/low hoses

Now, based upon my experience with the 92 DD which I converted, I whole heartedly recommend the variable orifice tube over the factory FIXED orifice tube. This $35 part makes a HUGE difference for R134a. To use, you need a 91+ system of pipes and evaporator which does not have the TXV. The orifice tube installs in the aluminum pipe beneath the exhaust mani, running along the frame rail top side.

Short of the ideal, the 89 system will perform acceptably with proper setup & correct (not overcharged) R134a.
 
Not to high jack but where is high side on an 89 240DL? Need to do some work on the ac but cannot find where to connect my gauges. Having a duh moment in this heat. Thanks. I did find the low side but is the high side also on the compressor?
 
My son achieved acceptable results with his (my old) 89 245.

China copy of condenser @ $100 to the door.
Sanden replacement compressor, bolt in.
Upgraded TXV under dash and possibly a tube or two to enable the conversion (there was a factory kit made to make these machines R134a friendly).
ESTER oil, not PAG for machines which were factory R12 and then converted.
New drier/receiver and new high/low hoses

Now, based upon my experience with the 92 DD which I converted, I whole heartedly recommend the variable orifice tube over the factory FIXED orifice tube. This $35 part makes a HUGE difference for R134a. To use, you need a 91+ system of pipes and evaporator which does not have the TXV. The orifice tube installs in the aluminum pipe beneath the exhaust mani, running along the frame rail top side.

Short of the ideal, the 89 system will perform acceptably with proper setup & correct (not overcharged) R134a.
Is there any chance you have more info on this TXV setup? My buddy?s 89 245 ac does not work, even after a thorough vacuum and recharge with r134a. I can feel the condenser get hot which tells me that his compressor is at least somewhat doing it?s job. I?m guessing the lack of cooling is from a TXV issue, or from a leaking heater control valve.

Also, as for the variable orifice tube, what were your results? I converted my 90 740 to r134a and although it sometimes will blow 40f, it takes a long time to get there. It likes to blow 60f most of the time. I?m thinking/hoping a variable orifice will help, but have read iffy results.

Not to high jack but where is high side on an 89 240DL? Need to do some work on the ac but cannot find where to connect my gauges. Having a duh moment in this heat. Thanks. I did find the low side but is the high side also on the compressor?
There is no high side fitting.
 
On my 89 240 my friend and I did fast and dirty 134a conversion. Basically vacuumed the system then added some of the newer oil, forget which one and the 134a via scale measurement. It blew ice cold, maybe 40 or less for 3 years. It must of had a leak because now I have no ac. I was going to recharge it today but was sure there was a high side fitting. Could only find one port, low side on the back of the compressor. Got tired of messing with it and will bring it to my friends shop on Monday. He says there is another fitting back there but I could not find it. That's my story
 
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