Simultaneous overheating and loss of A/C
 

Re: '94 SVX with 207K miles

I am struggling with a dual problem that occurs at same time. It only occurs after a steady drive at high speed but eventually in stop and go traffic which I am seldom in. The air is blowing cold and fairly quickly is no longer cooling. It seems lowering the temperature setting a degree or two gets it working again but only for a couple of minutes. By the time I have fiddled with the air controls I will see that the temperature indication has gone up. The temperature goes about half way from normal (about center) to the red line. It never makes it to red and there has never been steam. As long as the temperature is high the A/C does not work. If the temperature drops, the A/C will work again.

After the first occurrence, I replaced the thermostat and radiator cap. I completely purged the fluid and replace with new A-freeze mixture. The radiator and thermostat housing look very clean. There are no leaks: external, to oil or to compression. Both fans are running when there are problems.

I have now found a bit more of a strange set of circumstances. Once the problem has started, if I drive in third gear (set at 3) rather than drive, it will cool down and A/C will work. I went through 3 complete cycles of going to 'D' and back to '3' while driving at about 55 mph. Each time in D the A/C would quit after a minute or two and then the temperature would go up. Go the 3 and all would go back to normal. Now I can understand that a bit higher RPM will spin the A/C compressor faster and also the water pump, but this still seems very strange.

I have two specific questions:
1. Is there a temperature switch somewhere in the cooling system that shuts off the A/C compressor.
2. Has anyone experienced loss of water pump efficiency on a high mileage SVX or other Subaru? (Water pumps usually get noisy, leak or seize, but I have never seen one that pumps less than it should.)

Answers please or any other ideas.
Ken

Re: Simultaneous overheating and loss of A/C
 

If the condenser is not cooling the refrigerant, System pressure rises... the high side pressure gets too high, a safety switch opens the circuit and turns the compressor off.

The condenser fins could be dirty... like stopped up on the outside possibly with stuff. also the fins on the radiator as well?

I will have to think about all your good information when I get a little time.

Keith:)

Re: Simultaneous overheating and loss of A/C
 

I just had the same problem, though it ended up exposing itself on the Parkway. You probably have a coolant leak somewhere. It ended up being my upper radiator hose, and since replacement, no more temperature fluctiation, and ice cold A/C.

Re: Simultaneous overheating and loss of A/C
 

Had the exact problem a few years ago. The mechanic at the Dealership was replacing parts like crazy. Each time I'd leave with cold A/C the bang, gone. The problem vanished once I put in a new condenser.

Re: Simultaneous overheating and loss of A/C
 

Could be that the condenser is clogged up with dirt, thus cutting its efficiency and heat sinking the radiator...

Tom

Re: Simultaneous overheating and loss of A/C
 

im a subie newbie, but if increasing revs seems to cool the car more, it sounds like a coolant flow issue. A/C will always get turned off upon the ecu finding an overheat condition. again i dont know about this engine in great detail but working at a volkswagen dealership, many of our cars have plastic vanes on the water pump which go bad quite often and reduce flow, giving exactly the same situation you describe.

Re: Simultaneous overheating and loss of A/C
 

Sounds logical, but this logic doesn't apply.
Increasing the rpm also increases the heat output from the engine and there are no plastic vanes.
The ecu is not related to the safety switch for increase high side pressure.
Do you have a coolant loss?

Inquiring minds want to know:lol:

Keith

Re: Simultaneous overheating and loss of A/C
 

you might want to ck. radiator for clogged in side cores you can do this by useing infred heat gun.aim gun at radiator fins should be same temp all the way across you are looking for cold spots.it is a down flow radiator have not seen one cloged yet but ther is allways afirst time.and subaru water pumps use a stamp steal impeller on the water pump shaft not to say the impeller cant come loose from shaft .to ck this remove t-stat take radiator cap off start eng. see if you have good flow.if all else is good ck. head gasket if you need more info let me know W.C.Myers

Re: Simultaneous overheating and loss of A/C
 

Thanks for replies.

Update:
I checked the condenser and the part of the radiator front you can see. There is no clogging. The condenser fins are maybe 20% bent over on average, and could be losing some efficiency.

There is no fluid loss after 2 weeks since replacing components and replacing with new fluid.

Visually the radiator looks very clean for the little bit you see through the cap. I replace the radiator about a year ago. It was a used one with only about 15 K miles on it before owner went to an Ali radiator.

Laserx, A '92 with over 400k miles, outstanding! My two SVX's have a total of over 450K on them and I thought that was good. My '92 had become bit of a 'winter car' and will be retire soon, but I might drag my '94 for a whole lot more miles.
Ken

Re: Simultaneous overheating and loss of A/C
 

SVX ROO (Ken)

I sent you an e-mail this AM re the problem.

Re: Simultaneous overheating and loss of A/C
 

How's the prancing horse?

Re: Simultaneous overheating and loss of A/C
 

Hopefully it's not a head gasket failure or cracked head.

Re: Simultaneous overheating and loss of A/C
 

SVX ROO, I have 431,000 km or approx 259,000 miles, I put everyone one of them on the car, since I've had it since it was new. Hope you come up with a fix for your problem. I've change my signature to reflect the metric confusion.

Re: Simultaneous overheating and loss of A/C
 

Had this problem in my 95 Legend. Turned out all I needed to do was replace the condensor fan relay. Are both of the radiator fans kicking in? Only one of mine would and it would make the car overheat.

Re: Simultaneous overheating and loss of A/C
 

I have a new radiator, and just replaced the water pump since it was leaking. My AC goes hot and cold as well. The recirculate light will stay on for a few minutes then go out on it's own. In the morning when it is relatively cool outside, the AC works really good. When it is very hot outside, not so good. Off and on.