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Yes very commonly this is an obstructed expansion valve , evacuating and recharging it is the next step if that does not work then the valve will need to be replaced .
Before you go spending money go with the air conditioning on make sure the lecture cooling fans are running properly , and also take a garden hose and clean out the air conditioning condenser that's the part in front of the radiator because many times a dirty condenser or the cooling fan that is not working will cause high pressure
Why would you reckon it's working on defrost? Does that make a stronger or leaker case for an obstructed expansion valve?
Good morning Sean,
OK, new senerio. Both fans run when the system is cooling. But get this, I took it over to a friend who is a Chrysler mechanic. He put his test gauges on and told me I was LOW on freon. He added a full can and thre the pressures went where they're suppose to and the the system blows cold in the max position. On the way home, after the cabin had cooled, I switched to the regular run positions and the system quit blowing cold. I switched to defrost and it started again. Once it started I switched quickly switched back to max and it stayed cold. But if I switch to regular, which stops the system, then switch back to max, it doesn't start again. I have to restart it on defrost. If I start the car in the max position it comes on and blows cold. I have no idea what went on at Goodyear but I'm totally confused. I'm leaning toward a flacky control head. Is there electronics in the control head that can fail?
I don't have a scan tool. I have a digital Volt/Ohm meter. Is there a voltage I can measure to to monitor the a/c request?
I do have an OBD-II scan tool.
Is that what I need?
It does read data but it's pretty simplistic, ie ac refrig. monitoring is not supported.
If I go to Auto Zone and borrow/rent a scan tool what am I looking for?
So the ac/heater control head interfaces to the body control module? If there is a problem can the firmware in the body control module be reflashed or does it have to be replaced? What data parameters do I need to look at with the scan tool?
Does running the ac in the max position all the time cause a problem, i.e. will it freeze up or damage anything.