Air conditioner will not blow cold air, only warm air

Tiny
ALEX T
  • MEMBER
  • 1996 CHRYSLER TOWN AND COUNTRY
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 136,000 MILES
The clutch is not engaging. Disconnected the clip which seems to go to the compressor and checked with volt meter and there is no voltage present. I measured the resistance of the coil and found a value, so I connected a cable with a fuse and fed 12 VDC and the clutch worked and I had cold air for a few minutes, until I observed that the fan was not working and I chose to disconnect the cable for fear that the pressure would increase. What could be happening? I checked the clutch fuse (15 Amp) and the clutch relay (with external 12 VDC) and they are okay. What condition is missing for the clutch to work, just by turning on the cold air button? Thank you
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Wednesday, July 1st, 2020 AT 9:55 AM

11 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good afternoon,

I attached a wiring diagram for you. We need to do some testing at the relay to see why it is not engaging.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Roy
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Wednesday, July 1st, 2020 AT 10:32 AM
Tiny
ALEX T
  • MEMBER
Thanks for your answer. I have 12VDC at the base of the relay, I checked between them and with respect to the negative of the battery. The weird thing is that when I connect the relay, I don't feel/hear the coil activate, like when I feel it when I testing it with an external 12VDC source (I also externally tested the state change from NO to NC). Is it possible to "lose" the voltage when connecting this 78 ohm resistor relay? Another question, shouldn't the fan work, as soon as I press down the cold air button? I replaced the relay with a new one and the same thing happens. The coil is not activated.
Thank you
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Wednesday, July 1st, 2020 AT 11:16 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, with the key on, there should be 2 wires that have power. Check the terminals for this voltage. They both come from the fuse block as in the diagram I sent you.

Roy
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Wednesday, July 1st, 2020 AT 11:23 AM
Tiny
ALEX T
  • MEMBER
In the photo that is blocked with my hand, I am measuring the upper terminal of the relay base. Thank you
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Wednesday, July 1st, 2020 AT 12:05 PM
Tiny
ASEMASTER6371
  • EXPERT
No, black lead to good body ground. Then probe the terminals and make sure you have 2 terminals that have power.

Roy
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Wednesday, July 1st, 2020 AT 12:08 PM
Tiny
ALEX T
  • MEMBER
I checked voltage with respect to two different body ground and the result is the same. I checked for resistance at a point that I believed there would be continuity. Thanks for the support.
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Wednesday, July 1st, 2020 AT 12:37 PM
Tiny
ASEMASTER6371
  • EXPERT
Do not worry about resistance.

Okay, can you see the color of the wires for the terminals? One of the wires with no power goes to the ECM for a ground and the other goes to the A/C clutch.

Use you ohm meter and test the wire from the compressor to the terminals in the relay. When you find that wire, jump the wire from one of the powers to that wire. The compressor should come on.

Roy
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Wednesday, July 1st, 2020 AT 12:43 PM
Tiny
ALEX T
  • MEMBER
Okay, I did that test yesterday, but I was not very specific when I explained it in my first story; the compressor works, but it exceeded the pressure (I think I add extra of gas in it) and a green liquid came out of the head (maybe the previous owner added it to detect leaks), that's why I stopped the compressor. Replace a couple of o'rings and I left it ready to be able to detect why it does not activate automatically. In the last voltage measurement I made, I felt that the relay coil was already activated. I insist should they turn on the fans when I turn on the cold air conditioning?

Thank you for all of your help.
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Wednesday, July 1st, 2020 AT 1:16 PM
Tiny
ASEMASTER6371
  • EXPERT
The fans will come on when the high side gets to around 150-200 pounds.

The fact you overcharged it is no good.

You need to recover the freon and start from the beginning. Evacuate it for 45 minutes and charge it with exactly the amount needed.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Roy
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Wednesday, July 1st, 2020 AT 1:25 PM
Tiny
ALEX T
  • MEMBER
Okay, just yesterday with the help of a friend who has the equipment, we evacuated and added enough again; When the over pressure happened, it was the only time I saw the fans turn on. My problem is that the cold air conditioning does work not automatically. In your skill what other factors could prevent this from being achieved? Why automatically the voltage does not come to energize the A/C clutch?

Thanks again
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Wednesday, July 1st, 2020 AT 1:43 PM
Tiny
ASEMASTER6371
  • EXPERT
The pressure switch needs to be checked. Did you check the voltage to the switch?

I attached the diagram of the pressure switch. Check for the reference voltage to the switch.

Roy
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Wednesday, July 1st, 2020 AT 1:48 PM

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