Help with A/C Turning off--dealer in denial

[best2xford]

Here's a good dealer story...took it in because the AC shuts off now and then...Kerney Mesa Ford drove it 70 miles to tell me the couldn't replicate the problem. I told them it only happens when it it's over 100 degrees out, so knowing that, they drove it for 70 miles in 70 degree weather. Needless to say, the problem isn't solved and they haven't called back.

Has anyone else had their AC shut off, then come back on? It stays off for about 5-10 minutes, then will come back on. The pressure also goes down a alot during that time. Seems like something is freezing up, but unless I have something to cite, I don't think the dealer is going to help.

Any advice? Similar problem? Resolution?

Thanks,
Brian

 

[Shadowman]

Here's a good dealer story...took it in because the AC shuts off now and then...Kerney Mesa Ford drove it 70 miles to tell me the couldn't replicate the problem. I told them it only happens when it it's over 100 degrees out, so knowing that, they drove it for 70 miles in 70 degree weather. Needless to say, the problem isn't solved and they haven't called back.

Has anyone else had their AC shut off, then come back on? It stays off for about 5-10 minutes, then will come back on. The pressure also goes down a alot during that time. Seems like something is freezing up, but unless I have something to cite, I don't think the dealer is going to help.

Any advice? Similar problem? Resolution?

Thanks,
Brian

Hi Brian

I have make mention of this issue before and based on the manner in which she turns off I suspect (as has been the case with a few others) that the freon is a slight bit low as such during the warmer of days the compressor's head temperature climbs and shuts the system off; this is a design feature to save the compressor.

The ideal situation would be to have the system vacuumed down and then re-filled which will likely resolve all issues.

Just my 2 cents

Shadowman

 

[Jim Thommen]

Ford A.C. systems use a low and a high pressure cut off switch. The low pressure switch would open the circuit if low on refrigerant or a evaporator freeze up condition. The high pressure would open the compressor circuit if the system is overcharged or the condenser fan is inoperative. The other issue I have seen is the compressor clutch gap is set to far apart.With slight wear on the clutch plate will open up to far for the magnetic field of the clutch coil to be effective. Scan data can determine the switch status. If the vehicle is left stationary it will raise pressures and you can even turn the temp.control Knob to heat to increase the heat load on the ac system to locate the problem.

 

[Kayvan]

I have your solution.

The fins on your evaporator are having ice form on them. This happens in esp. high humidity or heat. Once the ice forms their is less room for air to flow between the fins (hence you lower airflow); then the system cycles off as the units temp drops too low.

The way to combat this is set the a/c knob one notch or 2 above the blue coldest setting. It will be plenty cold but above the 32F that will make it freeze. If its 100+ for hours on end, moveup to mid of blue/red zone once in a while to fully melt the ice.

The best analogy is old freezers that had the 4 wall s freeze up and you had less, less room till you had to defrost, P. 152 of this months Road& Track has a diagram of auto a/c systems.

This happens on old BMWs as well.

If this works, send me a present.