Well, if your model SHOULD blow colder, then there's a problem. A/C systems
are not that complicated.
The gas is compressed to a high pressure, heating it. It then passes through
the condensor (front rad) to cool it down, then flows to the evaporator in
the cabin, where the size of the pipes get larger. This reduces the
pressure, resulting in a decrease in temperature, hence air blown through
the evaporator is cooled. Then the gas circulates back to the compressor.
OK. If your shop has measured the high and low pressure sides and found them
correct, and the system won't blow colder than 60, then I'd suggest the
a) have the dual pressure switch checked. This is a switch that shuts down
the a/c if the gas pressure gets too low or too high. In town, the engine
runs hotter, and the a/c will start and stop to protect itself.
b) I'd also see if the condensor is covered in dirt and bugs. A good water
pressure clean can do wonders. Also, verify that the a/c fan is in fact
sucking air through the condensor, not trying to blow it forewards. Is
anything blocking air flow?
c) is the compressor clutch kicking in properly? Are you sure? Is the
compresser clutch slipping?
d) is anything blocking the air flow through the evaporator?
OK, repair shop went through compressor and replaced expansion valve a
second time. Replaced condenser---still blows 50 degrees on the freeway,
but stop at signals and it starts blowing hot air...get on freeway, cold
again, stop and go..hot air. Any other ideas??
When you are speeding along the freeway, the car's natural forward
motion is enough to drive air through the condenser coil to cool it off.
When you are stopped or going slow, the air conditioner relies on the
radiator's FAN to drive the air through. Apparently, the fan is not
working. The fix MIGHT be as simple as replacing the fan's fuse, if the
fuse had blown.
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