A/C blows hot air?

Tiny
WEEDER
  • MEMBER
  • 2003 NISSAN ALTIMA
  • 3.5L
  • 6 CYL
  • 2WD
  • MANUAL
  • 94,000 MILES
The compressor clutch does not engage. The A/C fuse is good but there is no power to the control side of the A/C relay. I suspect it is the climate control module as the temperature adjustment knob spins freely (more than 360 degrees) with no resistance. How would I confirm it is climate control module? Thank you.
Wednesday, July 5th, 2023 AT 11:13 AM

14 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
The fact that the knob spins 360 degrees means the HVAC controller is bad, here is how to replace it. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.
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Wednesday, July 5th, 2023 AT 5:27 PM
Tiny
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Thanks for the reply. The controller is no longer supplied by distributors. I will need to go to the wreckers and will get back to you.
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Thursday, July 6th, 2023 AT 4:24 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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I was afraid of that, let me know what happens.
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Friday, July 7th, 2023 AT 9:56 AM
Tiny
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  • MEMBER
  • 8 POSTS
The wreckers had a controller which I hooked up. All of the controls work but the A/C still does not work. The blower is still blowing warm air. Any suggestions? Thanks.
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Friday, July 7th, 2023 AT 10:24 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
The knob doesn't spin around, correct? When you turn the AC on can you lift the hood and use a flashlight to see if the compressor clutch is engaged?

This guide can help:

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

Please go over this guide and get back to us.

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Saturday, July 8th, 2023 AT 10:50 AM
Tiny
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  • MEMBER
  • 8 POSTS
The A/C controller appears to be working correctly. When the A/C is turned on the compressor clutch engages. I am assuming the next step is to check the low-pressure system. Can the pressure be confirmed by using a small can of refrigerant? Also, should the low-pressure sensor be checked? I could not find this sensor on the low-pressure line. Thank you.
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Saturday, July 8th, 2023 AT 3:48 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
Yes, you can check the low side with the recharge can, here is a video to help and I have included the low side pressure switch location as well:

https://youtu.be/uZrQCGwXfek

Check out the images (below). It does not say if it is the lower or high side pressure switch so let me know if the sensor is in the high side line. Please let us know how it goes.
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Monday, July 10th, 2023 AT 9:32 AM
Tiny
WEEDER
  • MEMBER
  • 8 POSTS
This pressure sensor is the only sensor visible for the system. It is located on a fitting attached to the condenser. The line from the compressor goes into the fitting at the top. A small line from the bottom of the condenser goes into the bottom of the fitting and then exits the fitting just below the compressor line. The sensor is located between the entry and exit points of the small line. It appears to be monitoring pressure on the line exiting the condenser.
What are your thoughts as to the problem and what to do now?
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Monday, July 10th, 2023 AT 11:25 AM
Tiny
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  • 8 POSTS
New information: I was just inspecting the A/C system and the compressor clutch did not engage. After turning the car off and on and the AC control off and on the compressor clutch is now engaging. The high-pressure line entering the dash feels cool but not cold. The line from the compressor to the condenser is very hot (too hot to hold a touch).
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Monday, July 10th, 2023 AT 2:32 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
Now with the compressor working what are the high and low side pressures? It still might be a little low on refrigerant. Also, when the compressor is not working see if the clutch is getting power?

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

and

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

Please go over these guides and get back to us.
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Tuesday, July 11th, 2023 AT 10:27 AM
Tiny
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  • MEMBER
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The low pressure was about 20 PSI before adding refrigerant. One can of refrigerant brought the pressure up to about 28. The system seemed to be running perfectly, blowing cold air. But thinking the pressure needed to be about the middle of the blue zone (35 PSI) I added more until the pressure was 35 PSI. The compressor started making noises (continuous groan) and was cycling on and off. Using the gauge hose, I bled the pressure back to about 30 PSI. The system cycling stopped but the compressor is still making a noise. Other than the noise everything seems to be working great. Should I bleed more off to quiet the compressor? Is there something else you'd suggest?
Sorry, but I don't have a high-pressure gauge. The compressor appears to turn on normally when the ac control is turned on.
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Tuesday, July 11th, 2023 AT 3:29 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Knowing the high side pressure can tell us more, if the pressures are correct and the compressor is making noise it may have too much oil in the system or the compressor is going bad.

Here is a generic guide to help you step by step with instructions in the diagrams below to show you how on your car:

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Check out the images (below). Please let us know how it goes
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Thursday, July 13th, 2023 AT 9:11 AM
Tiny
WEEDER
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After letting everything rest overnight, I turned the A/C on, and it all seemed normal. Cold air at the inside vent was 36F. I let the system run until the engine was hot, and the compressor started making the noise again. This indicated to me that the pressure in the system was too high when hot. I bled a little more out of the system and all seems well. Let it cool down and started again the next day. Compressor quiet and air cold. All seems well now.
Thank you for your help.
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Friday, July 14th, 2023 AT 1:22 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Saturday, July 15th, 2023 AT 10:19 AM

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