Have you checked the pressure in your a/c system? I would think that even if you fans didn't work, if you were driving more than 30mph, the moving air would still cool your system enough that you would get cold air. If it is not blowing cold when driving, you likely do have a leak or issue with your compressor.

 

I had a shop check the system, they said the compressor was bad. When I checked the system with an Autozone gauge, the system was way over pressured. The system has a dye in it, but I didn't see any leaks with an UV flash light.

Are the fans connected to the compressors performance?

 

You have a pressure control valve in your compressor and a high pressure switch on the high side under the air box above the transmission... High pressures or a blockage in the system or the compressor will shut down your cooling fans and blow hot air...
Also a bad expansion valve up by firewall may cause this problem also
Bad high pressure switch
Pressure control valve
These are new school systems you should read up on them ...not like the simple 2011 and under ones

 

I appreciate the reply
My system has very high pressure!
Firestone did a performance check and told me my compressor is bad. The compressor clutch kicks on when the AC is blowing and shuts off when I turn the ac off. The clutch spins freely by hand. No noises from anything.

I can change the expansion value and high pressure switch. If I change the expansion valve and find out its the compressor, Do I need to replace the expansion value again?

 

You need to check the pressures ..on low side and high side with gauges..
Don't just throw parts at it
It is more likely the pressure control solenoid valve inside the compressor is gone...which means replacement of it or complete compressor which is mainly done.
First step is to get pressure readings from low and high side.. Then read pressure charts... A set of gauges is your best investment.

 

Impoor,
My compressor was bad!
I replaced the AC compressor, condenser, expansion value and high pressure switch.
I vacuumed the system for 30mins and checked for leaks. Filled up the system with 20oz of 134A and 5.10oz pag 46 using our Robinair AC1234-4 recycle and recharge machine.

The fans still don't kick and the air blows mild. The fans are new and work. I've check all fuses and relays. Compressor kicks on, temp controls all work.

Any idea?

 

If you get a set of gauges 20-40 bones this read will help you
Car AC Pressure Chart | Low-Side & High-Side Pressure of R134a

 

Have you check engine temperature with a scanner opposed to dash gauge.?
Have you hoo
ked up a set of ac gauges on low and high side taken reading ?
There is a temperature sensor at back of evaporator up by firewall... Could be a scanner would tell you..
Also scanner would command fans on with ac low and high speed bidirectional
scanner
A cheap Vident ilink400 for gm can do it ..149-200$
Many bidirectional functions
Can you provide the low and high side pressure readings.?

 

Watch this funny guy explain how the 3 relays control your fans...check fan relay 1 has power when ac switch is turned on.

 

 

The confusing part reading the wiring is it says left side fan ... That is from the drivers seat...So when your bent over the rad it's thr fan on your right = low speed
Also in your fuse box the fan relay to the far right is Fan 1 relay low speed ...The jcase 30 amp fuse just right of relay is the low speed fuse.

Starting from the left when your looking at the fuse box
30 amp jcase fuse for fan relay circuit 2 high speed
Next Fan 3 relay
Next Fan 2 relay high speed
Next Fan 1 relay low speed
Then 30 amp jcase fuse for fan relay 1 circuit low speed

 

Low speed circuit operation is in series which means one component burns out nothing else works ..aka fuse ,relay, fan motor, power feed wire,(from computer dark green) or ground (behind right headlight)
Your fans will work on high speed since its a parallel circuit even if one burns out. That's why they work when you pull the CTS (coolant temperature sensor) connector off.
The pink wire from your ac dash control unit goes to the pressure control solenoid in the ac compressor ..a sillyscope lol tests it out
Then tan is just power to compressor
Hope this is clearer for you now..

 

@Impoor

Thank you for sending this all over.

Ill check this all out, low and high side pressure readings and I need to hook it up to a good scanner.
The ac system is a little cool. Colder air makes it colder. Driving around makes it a little bit colder.

I did change the HVAC controls when the original one shorted out in January 2023. I got a replacement from a salvage yard from like a 2008 or 2010 Impala. I've played around with the HVAC controls and its seems it all works.

 

@Impoor

I saw a post you made about a friends 2012 impala and the harness/pigtail was bad. My pigtail on the compressor was caked in oil, antifreeze, etc. It cleaned it up and plugged it back in.
Could this be my problem?
Where did you get the pigtail?

 

@Impoor

I saw a post you made about a friends 2012 impala and the harness/pigtail was bad. My pigtail on the compressor was caked in oil, antifreeze, etc. It cleaned it up and plugged it back in.
Could this be my problem?
Where did you get the pigtail?

May try Rockauto.com online.

 

You can't use the older dash controllers you need a 2012 or 2013 they are different the older ones... I'm surprised it works... Wiring is different No wonder they said the compressor was bad
Two less pins on the older ones.

 

@Impoor
I got a new Dash controller. It needs programmed as it shows --F° for the outside air temperature.

As of right now, the ac still blows a tad cool and the fans don't work. Nothing changed.

 

Rockauto.com online has the '12/'13 climate control module (with heated seats) for $121.79.

 

What kind of controller do you have dual zone. ..manual.or auto?
Did you ever think about your ambient temperature sensor
Manual push recirculate button and fresh air button at the same time with key on hold about 10 seconds ..turn key off.
Dual and Auto pull hvac fuse turn key on not start. Turn key off wait minute reinstall hvac fuse start car don't touch hvac controller ..it will reset you will hear actuators turning on off...when you hear no more sounds from hvac ..turn key off ...wait 15-20 seconds ..restart the car
Test all functions .

 

What kind of controller do you have dual zone. ..manual.or auto?
Did you ever think about your ambient temperature sensor
Manual push recirculate button and fresh air button at the same time with key on hold about 10 seconds ..turn key off.
Dual and Auto pull hvac fuse turn key on not start. Turn key off wait minute reinstall hvac fuse start car don't touch hvac controller ..it will reset you will hear actuators turning on off...when you hear no more sounds from hvac ..turn key off ...wait 15-20 seconds ..restart the car
Test all functions .

Dual controls, manual. 2012 impala ltz with the heated seat controller.
I did think about the ambient temperature sensor. Other people said they had to have it reprogrammed. I tried resetting it, nothing.

 

Start car push recirculate and fresh air buttons at same time ..hold 10-15 seconds it resets module.
Under header panel. Plastic cover held in with push pins ..left of hood latch ambient temperature sensor

 

Simplified testing in combination with the gm 3 relay video

 

One other reason the low speed fans will not work is how the low speed relay is installed...if you refer to the wiring diagram for the relays play close attention to pins 30 and 87...relay 1 and 2 (5 pin) go upside down and 3 high speed goes right side up...meaning you can read everything on it.. Not standing on your head lol
Most relays will show the pin numbers on them
If there is no power to all relays emission fuse 2 should be checked..
Last 15 amp fuse on row below ac relay

 

@Impoor
Fuses/relays all work and are installed correctly. I bought a new hvac control module and had to programmed. Everything else works, no check engine lights.

Fans still don't come on.
It was 74 degrees
Ac high is reading 100psi
Ac low is reading 85psi

 

Did you use parts that were used or new ?
How did you (program) the climate control module ?
I would like to know.
You have checked the wire from computer to low speed relay?
Ground behind R/ headlight and by trannie clean and tight ?
Can you explain everything no secrets.
Was the car running and ac on max and fan also engine warmed up when you got those ac pressure readings ?
After all these questions are answered l can give you a better answer to what is wrong.. Hopefully it's not the worst.

 

Did you use parts that were used or new ?
How did you (program) the climate control module ?
I would like to know.
You have checked the wire from computer to low speed relay?
Ground behind R/ headlight and by trannie clean and tight ?
Can you explain everything no secrets.
Was the car running and ac on max and fan also engine warmed up when you got those ac pressure readings ?
After all these questions are answered l can give you a better answer to what is wrong.. Hopefully it's not the worst.

Brand new climate control unit AC Delco. Chevy programmed it.
Ground is tight behind headlight.
Car was warmed up as I just drove 15 miles to the shop and let the car idea for another 5-10min. Ac was on max, and fan was on max. We even checked it at about 2k rpm and the reads were very similar.

Haven't check Ground by tranny? Where is that Ground?
Haven't checked wire from computer to relay

I was going to check the compressor pigtail to the pressure solenoid (back pigtail). When I changed the compressor, that pigtail was covered in dirt, oil, etc.

Let me throw you for a loop. I changed everything but the ac hoses and lines. I blew the lines out with air. I put 20oz 134a and 5.10 oz of oil back into the system. My shop guy said I could potentially have 6oz or 7oz of oil from what was left in the lines and evap.

 

Ground by trannie is under air box close to starter follow harness you will get to it..
Bottom left pin at relay and pin 59 at computer dark green beside dark blue under air box also
One thought is wiring also it is rare but is possible that the low speed diode has failed...you have to open up loom and trace where white and grey wires from fan motor meet with diode in between..l have never searched it out... Somewhere between fan motor and fuse box...l believe it is closer to fuse box if wiring diagrams are right..

 

Ground by trannie is under air box close to starter follow harness you will get to it..
Bottom left pin at relay and pin 59 at computer dark green beside dark blue under air box also
One thought is wiring also it is rare but is possible that the low speed diode has failed...you have to open up loom and trace where white and grey wires from fan motor meet with diode in between..l have never searched it out... Somewhere between fan motor and fuse box...l believe it is closer to fuse box if wiring diagrams are right..

Let me throw you for a loop. I changed everything but the ac hoses and lines. I blew the lines out with air. I put 20oz 134a and 5.10 oz of oil back into the system. My shop guy said I could potentially have 6oz or 7oz of oil from what was left in the lines and evap.

 

Probably even more...Your supposed to measure the amount of oil that drains from the compressor and add that amount in new compressor
Thats part of cooling performance not cooling fan operation unless ecm main computer commands system down.. As explained before low speed fan circuit is a series circuit so anything in the circuit that fails will shut it all down including( if ) ecm or bcm being the problem ..hope not
The diode is part of it also.
There is a ground also that is under the dash close to steering wheel for climate control module.
Without checking myself l don't know why these other guys can't figger it out.. They have the gauges and scanners sillyscopes multimeters.. But lacking something...Guess what.

 

@Impoor

I appreciate the back and forth communication. Thank you!

I recovered the system, all 20oz of 134a and 1.5oz of oil. I put the 20oz of 134a back in and BOOM, the system blows cold and the fans work on low and high.
The System had to much oil and the computer must of shut down the fans. I am going to do one more recovery this week and see how much oil I recover.
Assuming, I had 6-8oz of oil. Oil from the ac lines and evap. Everything else was changed.

I did fix all the grounds, chase wiring, checks fuses, pigtails and relays.

 

Glad to hear something made it work... The extra oil would effect the cooling performance. I believe the grounds was your problem with the fans ..since they work by grounding out.
BTW
Did you change the condenser filter with a new one ? Desiccant bag

 

Have you resolve this issue? I’m having a similar problem except it’s only one fan that will not run.

 

If one fan works and one doesn't, most probably it's the fan itself that's at fault. Check voltage going into each fan when the fans should be activated to confirm. If the faulty fan has no voltage, then look elsewhere in the circuit....

 

Where is the AC pressure switch located