Question about 1998 Ford Windstar
To diagnose problems, an A/C manifold gauge set is needed to read high and low side pressure readings. Avoid adding refrigerant with a simple charging kit like the ones sold at parts stores. Don’t add any stop leak, this can cause problems in the compressor, expansion valve or condenser.
Keep in mind that using an A/C gauge set and seeing BOTH high and low side readings can help in diagnosing the problem when you know what to look for. First, on a 134A system the high and low side service ports are different sizes. AC gauge sets have color coded hoses, the blue color coded hose has a connection that fits on the low side service port and the red hose has a connection that will only fit onto the high side. The yellow hose won’t hook up to anything if just checking the readings; it can be used to connect to a vacuum pump or attached to a refrigerant can or tank.
Normal readings on high and low side with AC OFF (static pressure) - Depends on outside temperature, but normally is between 80-105 PSI Normal low side reading with AC on high speed and MAX & engine at 800-1000 RPM’s - Ranges from 25-35 PSI - Note that on many Chrysler products a normal reading on the low side may be 15-25 PSI Normal high side reading ranges from 200-350 PSI.
Don’t assume that if adding little Freon is good that adding a lot is better! Overcharging just a little can decrease the performance of the system and possibly damage the compressor.
Both low and high side readings are lower than normal, this indicates a cars AC system is low on refrigerant and is under-charged. If both low and high side readings are too high, this indicates an overcharged system - too much refrigerant. This also can indicate that the condenser fan is not working, is too slow or the car is overheating and heat is transferring from the radiator to the condenser.
When the low side goes so low that it’s reading shows it is in a vacuum, the most likely cause is a bad expansion valve or blocked orifice tube. Another possibility is a restricted condenser. Blocked condensers are not as common as they used to be but if a compressor fails and comes apart inside the remnants can end up in the condenser causing it to restrict the flow of refrigerant.
When the compressor clutch is definitely engaged and the low side is high and the high side is low, the most likely cause is that the compressor is failing - it is not pumping sufficiently. Rarely an AC clutch could be slipping but usually this will be accompanied with a squeal or chirp.
Hope this helps. If the compressor did come on and pulled the R134a in to the system, you may still be low or you may be over charged. With out any pressure readings it's had for me to say what is the problem. You could also have a bad orifice tube ( expansion valve) Good luck and hope this helps.
Posted on Jul 03, 2009
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Posted on Jan 02, 2017
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