A/C not blowing cold.......

Drummer

Registered User
Just wondering if there is a vacuum line that could be messed up on my 90 for the A/C? The condenser is fine the dryer is new the compressor is new and one line going into the firewall is ice cold and the other isn't. Replaced the liquid line that contains the filter and had the system flushed. This is the R-134 er whatever the transition from the old A/C had as far as refrigerant. The air is cool but not as cold as it should be. It's freakin 98 degrees with a heat index of 102 around here. I thought I had all this sorted out. Oh and the low pressure switch on the dryer has been replaced to. Thanks.........
 
If one line is way too cold you might be short of refrigerant. How quickly does the compressor cycle on and off?

At the temperatures you are talking about it should stay on running for a long time.

If you don't have gauges then try and get the suction line feeling like a cold beer. If it's colder than that you are either short charged or you have a restriction in the orifice, usually caused by moisture in the system. If you didn't pull a vacuum on it before charging moisture could be an issue unless you did an old fashioned purge as you charged it.

Regards

Sean
 
If one line is way too cold you might be short of refrigerant. How quickly does the compressor cycle on and off?

At the temperatures you are talking about it should stay on running for a long time.

If you don't have gauges then try and get the suction line feeling like a cold beer. If it's colder than that you are either short charged or you have a restriction in the orifice, usually caused by moisture in the system. If you didn't pull a vacuum on it before charging moisture could be an issue unless you did an old fashioned purge as you charged it.

Regards

Sean
The system was purged by a mechanic. The orifice tube was retrofitted with a splice that has the filter in it. Since the filter is in the bottom of the "U" in the liquid line the tube was cut in half and fitted with this device. The old filter was and oily mess on pretty much clogged to a point that when the line was removed and I blew on it, air barely came out. The new compressor cycle just fine as far as the mechanic said. The condenser up front pus pressure washed to allow better air flow over the fins. Some of the were bent and I purchased a fin straightening tool from NAPA to remedy at least some of the pushed in fins. Not real sure the pressures needed to either the high or the low end of the system. The system has no leaks. I come to this conclusion from a leak test that was administered to the system before any more "topping off" was done. Is the factory limits, as far as refrigerant, the same on the SC as in any other Thunderbird. I ask this because of the lack of sufficient air flow over the radiator and condenser due to the supercharger inter-cooler. The car runs hot as far as to the touch goes but the temp gauge stays right around the "N" on normal on that specific gauge.
Seems to be a little cooler on the interstate also. The interior of the car is as black as pitch and the sun it brutal on it. I almost thought due to the heat on the inside the car was running cold air over heated plastic and by the time it came out the vents it was just "cool", not cold, air. That was just another one of my wild tangent theories.
 
A simple way to test if the condenser is not up to snuff is to spray it with a hose when your AC is on.

The water will add a considerable amount of cooling.

If the internal temp (get a thermometer in the vent so you know what it is exactly) drops and your car gets cold then you have to deal with the condenser.

That means it could be too hot or the fan is not getting the air through the condenser. Since the air comes through the condenser and then the radiator the radiator needs to be clean too.

Regards

Sean
 
Did the water hose thing and there is no difference in the cooling through the vents. Had the car running at idle in my driveway and put the hose at full speed in the front of the car to saturate the condenser. No difference. Actually the car only really gets half way cool when you are driving and is almost the ambient outside air temp. when at idle. Noticed also that the A/C clutch is running constantly and is not cycling like the A/C in my Jeep or my wife's car. Hmmmmmm.............
 
Then under-charged would be my diagnosis.

Regards

Sean
What are the pressures for the low side with the A/C on and on Max? I suppose I need to add more R-134. And I guess what is the pressure for the high side?
 
on r134 systems, on a 90 or so degree day, you'll usually see just above 200psi on the high side and 30, sometimes up to 45psi on the low side... if your system is low, and your compressor isnt cycling, you may have air and/or moisture in the system, causing "false" readings high enough to keep the compressor engaged... In a perfect world, the compressor should cycle every thirty seconds or so. You may also be getting evaporator freezing, which can also be caused by a moisture/air problem.
 
Back
Top