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air conditioner not quite conditioning

durk80

durk80

Member
Joined
Nov 17, 2015
Location
South GA
First, let me apologize for sounding even more neurotic than Woody Allen... The a/c in my 1990 240 is not blowing cold enough. About 2 years ago, I flushed the condenser and evaporator. I replaced both high and low side hoses, except for the one that goes from the condenser to the receiver dryer. The receiver dryer, expansion valve and 4-Seasons compressor were also replaced. I added an electric fan to the front of the condenser that is triggered to come on when the a/c is on. Of course, everything that I couldn't find a replacement for was sprayed with brake cleaner and shot out with an air compressor until it was clear. The entire system was put back together and put on vacuum until I could be sure there were no leaks (several hours). 3 cans of 134a were put into the system if I remember correctly.

The ambient temp today was 92 degrees. The chart says that the low side pressure should be 50-55 psi. My low pressure was 40 and High was 350--which seems rather high.

The air from the vent with a/c on max was 65 degrees. Not sure if there was a leak or not, I added more r134a to try and get the psi near 50 on the low side.

Is there anything I should look at that might give this reading, or should I just leave it and be happy that at least it is cooler than ambient temp?

I used this chart: http://rechargeac.com/how-to/ac-system-pressure-chart

Thanks as always, for your guidance.
 
Just charged my '90 245. The best temp I could get at the vents, with recirc on, was about 50 fahrenheit. And the car would then start to overheat at stop lights.

How many ounces were the cans you used?
The sticker on mine called for 2.9 lbs of R12. General rule for replacing with R134 is 80%, so 2.3 lbs is what I filled it to. I have no high side fitting so can't compare that. I saw low side between 35-50 psi. This was just last week, ambient temps above 80.
 
stevecole33 said:
Just charged my '90 245. The best temp I could get at the vents, with recirc on, was about 50 fahrenheit. And the car would then start to overheat at stop lights.

How many ounces were the cans you used?
The sticker on mine called for 2.9 lbs of R12. General rule for replacing with R134 is 80%, so 2.3 lbs is what I filled it to. I have no high side fitting so can't compare that. I saw low side between 35-50 psi. This was just last week, ambient temps above 80.
Click to expand...

That’s probably just your compensator board saying it’s overheating. But they added pusher fans in 1991 I think..

OP, Idle temps are hard to get low on the undersized weak Volvo systems. 93+ is pretty decent. You might have a faulty heater control valve letting heater core heat taint the system.
 
iHateVolvoPeople said:
OP, Idle temps are hard to get low on the undersized weak Volvo systems. 93+ is pretty decent. You might have a faulty heater control valve letting heater core heat taint the system.
Click to expand...

Thank you for the advice! I will check that out. Do you know if the cable be adjusted to completely close the valve, or must it be replaced because of internal wear? How do these things become faulty?

stevecole33
Just charged my '90 245. The best temp I could get at the vents, with recirc on, was about 50 fahrenheit. And the car would then start to overheat at stop lights.

How many ounces were the cans you used?
The sticker on mine called for 2.9 lbs of R12. General rule for replacing with R134 is 80%, so 2.3 lbs is what I filled it to. I have no high side fitting so can't compare that. I saw low side between 35-50 psi. This was just last week, ambient temps above 80.
Click to expand...

Thank you Steve, it's good to know that this is somewhat normal...For your overheating problem, have you tried putting an Infrared thermometer near the top of the thermostat housing? If you don't have access to one, I suppose you could 'very carefully' stick a conventional thermometer by the top hose inlet to get an idea of the temp when the gauge is in the normal position, and if it changes significantly when the a/c is on.

How is the fan clutch at low speed--can it easily be stopped with some rolled up newspaper? https://troubleshootmyvehicle.com/gm/4.8L-5.3L-6.0L/bad-fan-clutch-troubleshooting-case-study-3 This guy also has some troubleshooting for fan clutches if you care to check it out. Good luck and hopefully it will be an easy fix for you!
 
High side PSI seems a bit high to have good operation of the A/C system. Several things can cause this, too much refrigerant, poor air flow across the condenser, contaminated refrigerant or a faulty compressor. A quick test that will help sort this out requires running cool water from a garden hose across the condenser while the A/C is on. If the high side PSI drops and vent temperatures improve, air flow across the condenser is causing your problem.
 
Thanks for the suggestions. I've already bypassed the temp faker and haven't had time to put a temp gun on the engine. At some point soon it will probably get an electric fan.

Good luck with your heater controls. Hope you don't need to get too deep in the dash.
 
durk80 said:
Thank you for the advice! I will check that out. Do you know if the cable be adjusted to completely close the valve, or must it be replaced because of internal wear? How do these things become faulty?
/QUOTE]

They can leak inside past the closed valve and you'll never know, except you'll get heat competing with the ac trying to cool things. To rule this out, simply get something to pinch closed the top heater hose on the firewall under the hood. Hose pinch pliers or vise grips. If vent temps get cooler, you found a leaking heater valve.
Dave B
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I also recommend getting a double pass condenser. I swapped one in my 93 240 an im getting 39-43? temp at stop slights and around that in 80-90? ambient temp outside. I also added an Ls engine to my ac unit.
 
Texas240 said:
I also recommend getting a double pass condenser. I swapped one in my 93 240 an im getting 39-43? temp at stop slights and around that in 80-90? ambient temp outside. I also added an Ls engine to my ac unit.
Click to expand...

Link to condenser? I think the 93 (and 93 only) 240s were your standard parallel flow condenser correct? Too lazy to go look at mine.
 
dbarton said:
durk80 said:
Thank you for the advice! I will check that out. Do you know if the cable be adjusted to completely close the valve, or must it be replaced because of internal wear? How do these things become faulty?
/QUOTE]

They can leak inside past the closed valve and you'll never know, except you'll get heat competing with the ac trying to cool things. To rule this out, simply get something to pinch closed the top heater hose on the firewall under the hood. Hose pinch pliers or vise grips. If vent temps get cooler, you found a leaking heater valve.
Dave B
Click to expand...

Thank you Dave! I'll try that because I could never really get it that cool, and I much rather replace the valve than evac the system. And a simple test too:)
Click to expand...
 
Well this might help a bit. Looked at the GCP.SE catalog for 88-93 (group 87, page 1014 )

1259556 Condenser 4cyl -1990

3540373 Condenser 4cyl 1991- (LHD/RHD -1992)
3540647 Condenser 4cyl 1991- (LHD/RHD 1993- R134A)

1259556 Condenser DSL
Click to expand...

The 3** numbered one in the pictures definitely looks like 2 row, while the 1** numbered ones appear single (although hard to tell..)
 
That high side is too high. You could be overcharged. Or a restriction. I would feel around and see if there's a spot that gets hot, but not right after the hot spot.

I use a machine that puts in the correct weight.
 
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