I'm thinking the AC push button switch could be the culprit, or something in the control assembly, like the fan switch, since the compressor won't run with the fan turned off.

 

Also, want to add that the A/C light inside the car turns on when the air conditioner is on the on position and that the ac condenser fan turns on

 

You jumped 12V+ to the clutch and got the compressor to spin?

I'm guessing that you don't have 12V+ at the wire to the clutch when the AC switch is on?

 

Yes Pete. I jumped 12v+ directly from the battery to the clutch cable and it spin.
I dont have voltage at the signal cable that came from the car harness to the clutch cable.
Regarding your previous post I take off the dash bezel where the a/c controls are located and removed the a/c switch. I connected it back, started the car and the compressor engaged but quit after one or two minutes.

 

Uhhh...you mentioned the compressor would engage but quit after a minute or two, right? This tells us the compresssor clutch DOES have voltage. Since the fan works, this also tell us the two outside pins on the pressure switch are ok. Which means the AC switch should be fine too.

The middle 2 pins you checked have adequate pressure to start the compressor, but once the compressor draws down the low side, what happens? Alternatively, if the compressor increases pressure on the high side, did it trigger the pressure switch at 450?

That was why I asked what manifold gauge readings were you getting while it fails and shortly before. For example, did the low pressure continue to go down to 0, and how did the high side behave.

If the AC switch lights up when you depress it, it should be ok. (Pins 2-5 should have continuity when ON, but I wouldn't bother to pull it right now as the system at least works for a couple of minutes. I'm more interested in the pressures.)

I connected it back, started the car and the compressor engaged but quit after one or two minutes.

I tested the pressure switch and there is continuity between the two middle pins. So it tells me that there is adequate pressure to start the compressor. Fuses are ok, Relays are ok, pressure switch is ok. I thinks the only remaining part here is the AC Switch. Any way to test it?
Thanks!

 

AC pressure switch.

 

Yes, did you check the pressure switch? Should have continuity or not at certain pressures. A wiring diagram helps for things like this to isolate the problem.

And I think the light on the AC switch is separate from the activation circuit. Best to check terminals according to specs.

 

Have you tried ohmming the center 2 contacts of the pressure switch? Should have continuity when normal (~28-450 PSI), The 2 contacts on the ends of the oblong connector is the fan switch (high speed I think?).

did you use a manifold gauge set to check running pressures? Maybe it was low or high cutoff activated. I guess you can back prove the two said wired while it’s running.

 

HI
Thanks for all the recommendations. Question, does that car have only one pressure switch I think in the low side near de firewall?
Also, yes, I used a manifold gauge

 

The pressure switch is on the high side and looks like:

https://www.rockauto.com/info/1063/SW%209726C__ra_p.jpg

You should see continuity between the center 2 pins when the pressures are between 28-450.

So what pressure were you reading with the system off, running, and just before failing? For example, was it low pressure dropping to near zero, or high pressure going through the roof, etc. etc.

 

HI

I tested the pressure switch and there is continuity between the two middle pins. So it tells me that there is adequate pressure to start the compressor. Fuses are ok, Relays are ok, pressure switch is ok. I thinks the only remaining part here is the AC Switch. Any way to test it?
Thanks!

 

I would see if the clutch is even engaging. Your clutch is likely worn out. There are kits available to replace the clutch as opposed to buying the whole compressor. But if on time crunch, the compressor is a bargain.

 

HI
I tested the compressor connecting it directly to 12v+ and it engaged perfectly which tells me that the clutch is ok. ( Compressor was purchased brand new about two years ago, Denso brand)
When looking at the ac switch I removed the bezel from the dash and the switch came out. I inserted back again and started the car and the compressor engaged but it quit after maybe one minute or less.
I repeated the process of removing it and re inserted but it will not engage.

Later, maybe one hour, I was testing again and removed the ac switch, inserted back and the clutch engaged and quit maybe after 20 seconds. I noticed that the switch was a little bit warm. I don't know if I can make this but the switch have I think 6 pins
One row of five and a single ping on the next one
I just found only continuity between the first pin on the 5 row and the only pin on the next row but there was no difference if I press or depress the switch. Maybe I am getting continuity because of the bulb inside.

The light at the ac switch is working ok. If i press it the light will stay on; if depressed the light turns off.

I will try to find another switch since maybe the problem resides there.

AC pressure switch have continuity between two center pins
Fan is turning on
blower is turning on

Thanks!

 

For intermittent compressor operation priority troubleshooting:

1. Inspect volume of refrigerant
2. Inspect cooling system for refrigerant
3. Pressure switch
4. A/C amplifier
5. Thermistor
6. wiring and wiring connections

For the switch if you number the terminals like this
2-------1
6-5-4-3
5 to 6 continuity with switch ON. The other terminals are used for the light bulb and the dimming of the bulb when the lights are on.

 

Well, its been almost two months since my problem started and as of today and because of this pandemic I haven't been able to repair it.
The update:

Parts changed:

-A/c amplifier
- a/c switch (turn on and off the compressor)

I keep making some troubleshooting and found that the wiring from the compressor to the relay box is ok
all the fuses are ok
I applied voltage to the relays, the coil is working and there is continuity
The A/C switch light is on ( of course if its in the on position)
there is refrigerant in the system

Its like a strange thing because sometimes ( when I first start the car) the compressor engages but then it stop working few seconds later ( cold air blows out)
The compressor is about 2 years old (denso)

I have found that there is no signal coming from the inside components of the car to the relay box so it can activate the signal to the compressor.

Any advice on this one?

 

Test your pressure switch.

 

I tested it and there is continuity on it so it means there is adequate pressure on the system.
Thanks

 

A bad thermistor would stop the compressor from engaging. DrZ's list is a good reference.

 

The thermistor is the sensor that is attached to the evaporator core?

 

Yes, that's the one.

Here's a photo of mine.

 

You said your AC fan turns on though? The fan should not turn on if the compressor is disengaged if I remember correctly, even if AC is on.

A bad thermistor wouldn't let the compressor engage, but the fan wouldn't turn on either.

 

The condenser fan and magnetic clutch are both turned on by the MG Relay, so if the condensor fan comes on it may be a wiring problem between the relay and clutch.