AC clutch not engaging

Hi everyone

My A/C clutch just stopped kicking in the other day.

- checked refrigerant level- it is normal
- checked/tested the fuses- Normal
- swapped relays(honk relay) - still not kicking in- honk relays works
- tested pressure valve - normal
- checked if all the electric connections to the compressor are tight and snug

the only two times the clutch kicks in are;
- when I jump the relay switch, and
- when I slam the hood down very hard!

Any help appreciated.

2010 Taco.
btw- no where near a dealership nor a good A/C shop. Troubleshooting things on my own with the help of Tacomaworld forums

thank you

Marcus

 

@CurtB
@Jimmyh

I'm thinking the low pressure switch?

@spicy12345, how did you test the refrigerant level on a non running system?

 

Have you verified ground all along the circuit?

The hood slamming bit tells me that you more than likely have a bad/loose/corroded pin in the PDB. Pull the relay out and look carefully for any sign of corrosion.

 

Could it be a problem with the electrical connection in the dash board? We had this happen on another car, but the clutch didn't move even when you sent 12v directly to it with a jumper wire. If I understand you, your ac clutch does activate when you send power to it manually. So it must be an electrical problem, not a mechanical one, and it is somewhere between the heater controls and the ac clutch.

 

Did you check that you have power at the relay?
Super easy to jump the two wires on the low pressure switch to rule that out.
Agree that working with hood slamming sounds like a connector issue.

 

yes, sent power to the clutch manually. I stuck a copper wire where the relay is.


that could be it. I noticed the heater controls works sometimes on high only- but it is intermittent problem(comes an goes). I ordered a Blower Motor Control Module / Resistor kit.

 

Yes, the relay has . tested with voltmeter. tested the fuses as well for continuity and power.

Yes. jump the lower pressure switch -stuck a wire in it. the clutch engages. tested for power too with voltmeter 11.48 volts.


which connectors should I check? I removed the connectors to the compressor, cleaned it - two connectors. and did the same for the low pressure switch connector. Did I miss any?

thanks

 

Did you check continuity across the pressure switch? I get that you jumped the connector side to verify the clutch is working, but what about the switch being bad. It is a simple open/close switch. You should have continuity across it since you verified the charge.

 

How do I check continuity across the pressure switch? I checked the connector side for continuity and its beeping.

another question: when I jumped the connector side (by passed the pressure switch), the clutch turns. does that mean pressure switch is good or bad?

thanks for your help

 

Fix the blower first.

 

What that means is that the refrigerant charge is low or Pressure switch is defective.

You read the switch across the terminals on the Ohms setting on the meter. A closed switch will read near zero ohms an open switch will read OL or a very High resistance.

If the switch is open ( which it appears that it is ) the clutch will not engage. These pressure switches rarely fail and you most likely have a low refrigerant charge. IF the refrigerant charge is in fact good then the pressure switch is defective.

How did you check the refrigerant charge? Be specific.

Maybe @CurtB will chime in.

 

Hey. That means the clown in post two was at least warm with his guess.

 

You are way too hard on yourself. Great minds think alike!

 

Not quite sure I am following you. Couple things. If the clutch is spinning free then it is not engaged. Easiest to check when the engine is running - look at the end of the clutch, it will not be spinning. I'm assuming the clutch is not seized else you would be hearing it from the clutch assy when the engine is running. With the ignition in the on position and the AC turned on the fan should be running and putting air out of the vents, i.e. fan is good. Keep the key in the on position from the fan check. You swapped relays with a known good to no affect so you know it is not a relay problem. You had the Freon level checked so you know you have a charge. When you jumped the connector on the "truck wiring" side of the pressure switch you heard a "click" from the compressor/clutch area, yes?? It is plainly audible. That would confirm the clutch works. As for the pressure switch. If it is not working, you will not get power to the relay or clutch. To check the pressure switch probe the switch contacts for continuity - set the meter on ohms or diode check. You are looking for a 1 ohm or less type of reading.

That it works occasionally with a hood slam is curious... Make sure you do the pressure switch check when the clutch is not actuating just in case it is intermittent.

If the pressure switch checks good, then with the key on like above, start wiggling, pushing, pulling the wires at the various connectors looking for a broken conductor - typically at the connector.

That really covers all of the basic checks you can do.

Good luck!

 

How was the level checked if the compressor was not engaged? Did you have a gauge manifold connected? If so what were the readings?

I agree with either low freon or bad pressure switch. Slamming the hood making it run sounds like a wiring problem.
Perhaps 2 different problems?

 

Actually, I could see where slamming the hood could 'jiggle' a dodgy pressure switch for a bit.

 

Possible. A few love taps on the switch would be a quick way to find out.

 

I checked the refrigerant level again.

Here is how I checked the refrigerant level specifically:

Ambient weather; 29C or 84.2F humidity level 31%, cloudy day. I don't have a thermometer. these readings were from the weather channel

1-connected manifold;(truck not started yet) static readings were; about 80 on both side
2- started the truck; clutch wouldn't engage(click). shut off the engine, took the relay out, stuck a wire were the relay was. started the truck again: clutch engaged and cold air coming out of the vents.
3- manifold readings were; 25 low side, 175 high side.
4-let it run for a bit;increased to about 2500 rpm. manifold readings didn't change much: 26 low side, 180 high side.

I think this falls within the normal parameters. correct? or is it little low to cause this?


thanks

 

2- started the truck; clutch wouldn't engage(click). shut off the engine, took the relay out, stuck a wire were the relay was. started the truck again: clutch engaged and cool air coming out of the vents

Per above - the system "works" but something is amiss, this is great goodness. If you now check continuity across the pressure sensor and it is good then you are most likely chasing something between the dash switch and the relay - most likely the dash switch.
If the sensor shows open then either the sensor is bad or the charge is low. I can't speak to whether or not your technique/results for checking the charge is correct.
All things considered, I suspect you are a bit low on the charge..?

 

Have you tested the relay? If the system works without it and your wire test shows it gets power then it may have failed.