AC Compressor only engages when Low pressure switch is jumped Topic is solved

[abscate]

I think I've confused you Chuck with the term "1 ohm". My multimeter says "1" ohm when there's 100% resistance, a broken circuit and 0.00 ohm with no resistance, connecting the two multimeter probes. My pressure switch has infinite resistance between the two pins all the time, ac running or not. I will try to replace the pressure switch (will it leak refrigerant for a few seconds while I'm unscrewing it? I'd better be fast? ). Thank you Chuck and everyone else! Sorry for fooling you with my "1 ohm" statement. I thought 1 ohm ment infinite resistance as that's what my multimeter says....

Yes, until we agree on what the measurements mean we are speaking different languages.

With the low pressure switch out, it should read INFINITE resistance, or open circuit between the terminals.

[Chuck W]

I think I've confused you Chuck with the term "1 ohm". My multimeter says "1" ohm when there's 100% resistance, a broken circuit and 0.00 ohm with no resistance, connecting the two multimeter probes. My pressure switch has infinite resistance between the two pins all the time, ac running or not. I will try to replace the pressure switch (will it leak refrigerant for a few seconds while I'm unscrewing it? I'd better be fast? ). Thank you Chuck and everyone else! Sorry for fooling you with my "1 ohm" statement. I thought 1 ohm ment infinite resistance as that's what my multimeter says....

Well, at least we're on the same page now. My multimeter reads "OL" (over limit) when there is infinite resistance (a broken circuit).

The pressure switch is mean to be replaced with no (or very minimal) refrigerant loss. The only loss may be when the check valve is close when removing/installing a switch. (It has a Schrader-type valve, like the fill port on the AC system). There will be no measurable refrigerant loss while swapping the switch.

[LOB]

Unfortunately there seems to be some other fault as well because my AC, while the pressure switch is jumped, is running constantly even if I put maximum heat on the ECC.

[BEJinFbk]

I’m not sure that absolutely means that you have a problem.
Before automatic climate control, it was standard operating
procedure to run max heat and AC simultaneously in very
humid conditions to keep the windows clear. AC pulls
moisture out of the air very nicely. Have a look at some
ancient owners manual. All the cool kids were doing it!

Is it putting out enough cold air to bring the interior
temp down far enough that it should disengage?

[Chuck W]

The AC runs/cycles when the ECC is set to full "Defrost", no matter what the temp setting is.

[LOB]

I kept my ECC set on maximum heat for 5 minutes but the compressor clutch kept engaging all the time when the pressure switch was jumped . Strange....

[Clemens]

What I can tell you from experience: No, the compressor will not run all the time even in very hot environments and both climate controls set to the lowest level.
Other than that, I have nothing to add.

[LOB]

A new low pressure switch solved all problems! Thanks a lot Chuck and everyone else contributing!

[misha]

What I can tell you from experience: No, the compressor will not run all the time even in very hot environments and both climate controls set to the lowest level.
Other than that, I have nothing to add.

With system fully charged,when settings are on lowest level and slider out of AUT position for blower on ECC equipped car...compressor will run all the time.
It will start to cycle in case that you set dials on...let's say 22 degrees....and temperature in cabin is reached 22 degrees.
Untill the temperature inside the cabin is not reached the temperature which is set on dials,compressor will not cycle on fully charged ac system.

If compressor cycles frequently...the system is low on freon,temp sensors (cabin or duct)are dirty or faulty or there are stored codes in ECC unit(blinking ac/rec lights on every start-up).
When system is at 50% low on charge...the compressor will cycle frequently on every setting....AUT or manual.

[Clemens]

Misha, I think you are right with this as usual, but there surely is the thermal protection switch that can kick in and disengage the compressort even if everything is working properly and the settings at full cold