Air con blows cold only on freeway.

[DanDombrowski]

All of the other advice is good, but I think the answer is pretty obvious to me.

If you're running cold on the freeway (as in, its working properly), but not at idle, its either a problem with airflow across the condenser, or the compressor isn't working well at lower RPMs. Checking the high side pressure will sort out the second scenario.

Now, you say you had the aux fan replaced, but if the condenser is clogged with dirt/debris, it won't matter much. Take a look at how much dirt you see in there, and maybe try to hose it out from the back.

Here's a quick test you can do before you buy any new equipment - at idle, turn on the AC and spray a garden hose on the condenser. If the AC turns icy, you have an airflow problem. If it stays the same, you have a pressure problem. Good luck with it!

[BennyM]

Hey Brian,
The mechanic actually measured the temp as you described when he recharged the system. He told me it was supposed to be around 40F, but was inexplicably higher.

After driving the car around the city, I checked the heater valve hoses. They all seemed warm from the ambient temp under the hood, but not hot as I would expect if the valve were interfering.

[Barney Paull-Edwards]

Pollen Filter!!!!!!!!!

[bsell]

Hey Brian,
The mechanic actually measured the temp as you described when he recharged the system. He told me it was supposed to be around 40F, but was inexplicably higher.

After driving the car around the city, I checked the heater valve hoses. They all seemed warm from the ambient temp under the hood, but not hot as I would expect if the valve were interfering.

I like Dan's 'shade tree' idea of spraying water on the condenser to see if your problem is a heat-removing problem.

Yet, you may have something as simple as an air-flow problem caused by a dirty cabin filter. The extra air pressure at the cowl could help blow more air through a clogged cabin filter, making the inside of your car cooler.

I take it your pressures were good but the temp at the vents was warmer than it should be? I would figure inadequate heat-removal would make the high side pressures high while a clogged filter would make the low side lower. Any idea what the pressures were?

Brian

[Ross]

If there is a blockage in the heater core/evaporator area the airflow will be diminished as well. I vote for a weak compressor or a very dirty condensor which the mechanic should have checked while replacing the aux. fan.

[BennyM]

Right, except I replaced the exhaust fan. So, it's my fault for not checking.

[BennyM]

I replaced that a couple years ago. I will check it again soon.

[BennyM]

Thanks Dan. I did the test twice and experienced no change in temp. Guess it's a pressure problem. I should probably clean out the condenser anyway, since that's probably never been done, but from what you're all saying, I'll probably have to replace the compressor, huh? Boo that.

[Milkboot]

Would this apply to most cars? Been borrowing moms Jeep while i work out my own problems with my lil e34 and it sounds like she has the same basic problem


Been jumping curbs at the corner just to keep on moving to get the cool air going!

[Bin_jammin]

I'd gamble on an issue with the aux fan, either the fan motor or the resistor. At idle it's not functioning properly and the high pressure switch is turning the system off. Cruising on the highway will aid the operation of the aux fan, making you cold.