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  #1  
Old 05-11-2007, 05:09 PM
shimmersky shimmersky is offline
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Unhappy a/c blowing cold for a while then hot

hi everyone
so im starting to feel the heat here in vegas its over 100f today
something funny started with the a/c the other day
driving along and the a/c is working fine
then all of a sudden it just starts blowing ambient air
no more cooling!!

i thought it might be a refrigerant charge issue so i purchased a bottle kit type thing with a gauge to tell you if it needs a charge or not, it says it wont read correct if it is over 85f
and it said my system was in the red or in need of mechanical service(high pressure reading at the low a/c port)

the car seems to cool just fine until it seems to just get too hot(ambient) and then somthing stops it from blowing cold air
if i let the car sit for a while and cool down(engine) and start with full a/c it seems to work fine

i know this car has a pretty unique cooling system, but does anybody have any ideas or advice
maybe i just need to take it to my tech and have the system recharged

stay cool
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  #2  
Old 05-11-2007, 05:27 PM
cdvs cdvs is offline
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Check your fans for proper operation.

There are low and high pressure cut off switches.
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  #3  
Old 05-11-2007, 09:14 PM
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1) low reading on the high side= a) lack of refrigerant or broken/leaky compressor discharge valves.
2) high reading on low side= a) expansion valve stuck in open position or overfeeding
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  #4  
Old 05-12-2007, 01:41 AM
blue thunder blue thunder is offline
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This probably won't help out any but I wanted to relate my story so maybe it might. I have not had a consistent working A/C system for many years. Blows cold for a short time only and the cooling aspect shuts off. The fan still blows fine. I took it to a dealer about two mos. ago and everything checked fine idling in the garage. However, out on the road driving the air barely even came on. Shortly after this my idler pulley started to seize up making a squealing noise (the belt) until after a few days it started to smoke. I cut off the belt and installed a new pulley and ac belt. Guess what. The last few days my air stays on full time. I drove over 100 miles today and it worked fine. After all these years. Sometimes you get lucky. Maybe my old pulley was not performing correctly. Good luck with you're case.

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  #5  
Old 05-12-2007, 10:02 AM
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If the coolant temp gets too high the AC compressor will automatically shut down until the coolant temperature comes back down.

Try taking out the front grill for more airflow the next time you are out cruising on a 100 degree day and see if that helps. I remember another member here from arizona did that with good results.
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  #6  
Old 05-12-2007, 10:00 PM
shimmersky shimmersky is offline
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interesting

all very good info
thanks to those that have replied
im leaning towards the coolant getting too hot
the system works fine here in the morning and at night and all other times
the only time it kicks off is when its real hot out and im sitting in traffic or going up the hill to my house

although i dont disregard a component failing in the system it just seems to be linked to ambient temps

any more ideas keep them coming
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  #7  
Old 05-12-2007, 10:56 PM
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At the risk of sounding like the ignorant less-than-one-week-SVX-owner that I am, how does one tell the A/C is on? I haven't seen any A/C buttons yet, although I'm discovering a new button or feature every time I take the car around the block.
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  #8  
Old 05-12-2007, 11:28 PM
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Quote:
Originally Posted by shimmersky
all very good info
thanks to those that have replied
im leaning towards the coolant getting too hot
the system works fine here in the morning and at night and all other times
the only time it kicks off is when its real hot out and im sitting in traffic or going up the hill to my house

although i dont disregard a component failing in the system it just seems to be linked to ambient temps

any more ideas keep them coming
The AC is operated when you select the auto function and set the temp colder than the ambient cabin temp. The fan will automatically adjust its speed, and vent shifting. You can also adjust fan speed with the hi lo buttons.
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  #9  
Old 05-13-2007, 10:29 AM
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immortal_suby immortal_suby is offline
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Quote:
Originally Posted by Crazy_pilot
At the risk of sounding like the ignorant less-than-one-week-SVX-owner that I am, how does one tell the A/C is on? I haven't seen any A/C buttons yet, although I'm discovering a new button or feature every time I take the car around the block.
Like UPnorth said, Def or Auto buttons will activate the AC compressor when the selected temp is below ambient temp. You also see idle RPM increase and the fans come on. Also if you look under the hood at the AC compressor you'll see the pulley lock has engaged and the compressor is actually turning instead of the pulley just free spinning.
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92 Ebony LS-L. ecutune stage1v4, motorsport 1pc pulley. Garage Queen - sold to Dad in upstate NY 155,000 miles
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  #10  
Old 05-13-2007, 03:06 PM
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You are probably getting enough air moving across the coil while driving but not enough at a slow or stopped position. I would check if the condensor coil is dirty.
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  #11  
Old 05-13-2007, 06:36 PM
shimmersky shimmersky is offline
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how does this work

Quote:
Originally Posted by immortal_suby
If the coolant temp gets too high the AC compressor will automatically shut down until the coolant temperature comes back down.

Try taking out the front grill for more airflow the next time you are out cruising on a 100 degree day and see if that helps. I remember another member here from arizona did that with good results.
how does the coolant temp affect the a/c system
if the car gets too hot is it a protective measure to shut down the compressor??

im not exactly sure as to the theory of operation with the a/c but how is the cooling system hooked in with the air con system

i have just installed a new silla radiator and just did a coolant flush as well

all very good info thanks
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  #12  
Old 05-13-2007, 07:16 PM
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dannmarr dannmarr is offline
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Actually, if the A/C system has high head pressure (unable to extract enough heat to the outside and condense the refrigerant gas back to a liquid ) then the compressor will shut itself down as a safety measure. What causes high head pressure? Dirty coil, broken fan, fan motor, belts, anything that would prevent the A/C from cooling down the (high pressure/high temperature) refrigerant.
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  #13  
Old 05-13-2007, 07:56 PM
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immortal_suby immortal_suby is offline
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Quote:
Originally Posted by shimmersky
how does the coolant temp affect the a/c system
if the car gets too hot is it a protective measure to shut down the compressor??

im not exactly sure as to the theory of operation with the a/c but how is the cooling system hooked in with the air con system

i have just installed a new silla radiator and just did a coolant flush as well

all very good info thanks
there is a coolant temp sensor that the AC diagnostics system reads from (located near the heater core according to the tecdoc) that will shut down the compressor as a protective measure when the coolant temp is too high.

http://www.subaru-svx.net/photos/files/How-To/14349.pdf
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92 Ebony LS-L. ecutune stage1v4, motorsport 1pc pulley. Garage Queen - sold to Dad in upstate NY 155,000 miles
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  #14  
Old 05-13-2007, 08:17 PM
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Quote:
Originally Posted by shimmersky
how does the coolant temp affect the a/c system
if the car gets too hot is it a protective measure to shut down the compressor??

im not exactly sure as to the theory of operation with the a/c but how is the cooling system hooked in with the air con system

i have just installed a new silla radiator and just did a coolant flush as well

all very good info thanks
The radiator coolant and the AC cooler are in no way directly connected, as you must have noticed, and as the cooler is in front of the radiator, there should be no affective transfer of heat, radiator to cooler, particularly when on the move.

The dual fans are arranged and controlled in tandem, with the air conditioning included within the equation. The only occasion when the engine temperature could be rated as having an affect, would be if the overall system was operating beyond normal limits and capacity, e.g. under conditions of extreme ambient temperatures.
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