My 2004 Liberty just started this a couple weeks ago. When sitting still, the AC blows hot air. It cools down nicely when you start moving. This makes traffic lights and people who don’t go when the light turns green VERY annoying. While waiting, I can hear the compressor coming on and off. Thinking perhaps the radiator fan wasn’t coming on, I looked at the radiator fan fuse, 40 amps, and it looks fine. I even checked it with an ohm meter. With the car sitting still, engine running and AC on, I don’t think the radiator fan is going. Maybe one of these two relays?
Important details (or not)
5 speed transmission
“What color is the car?” Blue.
Two wheel drive. (alas, it’s a Jeep in style only)
There is no air blowing across the condenser when you are sitting still so no cooling. There is no fan running when you are sitting at a light, I don’t think that is correct. Are there 2 fans on this car? The electrical schematic I found on Autozone’s website shows a separate AC cooling fan and relay (in the Option Box) driven by a “triple pressure switch” in the AC pressure line. If the relay failed, the fan wouldn’t run and the system wouldn’t cool at idle. If half the triple switch failed, the same would occur. Find the relay and replace it. If that doesn’t fix the problem, the pressure switch may be at fault. I don’t think that can be replaced without discharging the system… and an AC tech should do that to recover the refrigerant.
Radiator fan motor failure is most common. Test for power to the fan motor with a volt meter or test light; yellow wire= high speed, dark green=low, black/orange=ground.
I had a similar issue, not really blowing hot but car definitely warmer at slow speeds and stoplights. It ended up my fan was not running due to a bad blower motor resistor. If you have higher speeds that work and blow out cold air cast my vote for a new blower motor resistor.
Thanks for the tips. I’ll look into it.
An AC just moves heat from one place to another. The part that it removes the heat from gets cooler. But that won’t work if it can’t remove the heat from the hot part as fast as it cools the cool part. Either the fan in the engine compartment isn’t coming on in stop and go traffic, or it isn’t turning at the right speed. Have you actually opened the hood and inspected the fan to see if it is turning or not when this symptom is occurring?
The electric condenser fan should be cycling on whenever the compressor clutch is engaged.
A low refrigerant level can also cause a problem like this. At 11 years of age a little (lot in some cases) refrigerant loss is to be expected.
+1 @ok4450 - Low refrigerant.