A/C Issues 2010 V6 Mustang

[crowdkilla]

Hi all, I'm having some issues with the A/C on my 2010 4.0l v6 mustang. I've only had the car for about a year and the A/C worked fine last summer but this summer it will randomly only blow hot air, then revert back to cold, then hot. Very intermittent. On hotter days, it won't blow cold air at all, then on days where it's only 75-85 degrees it will cycle between blowing warm or cool air.

Had a telltale knocking sound coming from the dashboard when I turn on the fan/ac, so I figured it could be an actuator issue. I replaced the heat temp blend actuator and it didn't solve the issue.

Scanned it and got code P0645, A/C Clutch Relay Control Circuit, and P0480, Fan 1 Control Circuit.
I swapped the relay for the A/C Compressor and it didn't seem to fix the issue either.

When looking at my A/C compressor in the engine, I can see it freezing up and shutting off, then randomly kicking on and spinning again a minute later. It seems to be short cycling, but just taking wayyyy longer to kick on in the hotter weather. When it short cycles like this, it also causes my engine's idle to drop down dangerously low to stalling.

Anyone have any experience with this? I don't have a pressure gauge to hook up to it. I did use an old cap from refrigerant to look at the pressure from the low side, and if anything it looks like my refrigerant is actually overcharged. No leaks, etc. Is it electrical?

 

[86GT351]

1st step is pressure gauges. Will tell you alot. If the compressor is freezing there is a freon level issue.

 

[golkhl]

Might be a bad a/c pressure switch…..

 

[Iceman62]

At my age, I just take it into the local shop...they have the tools/talent to troubleshoot & fix.

 

[Mpedersen]

I just had this problem with my AC ….but I didn’t have any codes from the AC. Ford dealership had to rewire the ambient temperature sensor. Drivers side by the bottom of the radiator. Ice cold now!

 

[Robert Larimer]

Hi all, I'm having some issues with the A/C on my 2010 4.0l v6 mustang. I've only had the car for about a year and the A/C worked fine last summer but this summer it will randomly only blow hot air, then revert back to cold, then hot. Very intermittent. On hotter days, it won't blow cold air at all, then on days where it's only 75-85 degrees it will cycle between blowing warm or cool air.

Had a telltale knocking sound coming from the dashboard when I turn on the fan/ac, so I figured it could be an actuator issue. I replaced the heat temp blend actuator and it didn't solve the issue.

Scanned it and got code P0645, A/C Clutch Relay Control Circuit, and P0480, Fan 1 Control Circuit.
I swapped the relay for the A/C Compressor and it didn't seem to fix the issue either.

When looking at my A/C compressor in the engine, I can see it freezing up and shutting off, then randomly kicking on and spinning again a minute later. It seems to be short cycling, but just taking wayyyy longer to kick on in the hotter weather. When it short cycles like this, it also causes my engine's idle to drop down dangerously low to stalling.

Anyone have any experience with this? I don't have a pressure gauge to hook up to it. I did use an old cap from refrigerant to look at the pressure from the low side, and if anything it looks like my refrigerant is actually overcharged. No leaks, etc. Is it electrical?

Does your radiator fan run continuously when the A/C is on? If it doesn't the compressor will cut out from over pressure and the hi speed fan will come on to reduce it and the compressor will come back on. It will keep cycling like that. The solution is fixing your low speed fan. Most likely the fan resistor has failed. The engine nearly stalling is from the stress of starting the compressor when its pressure is too high.

 

[Samikanaan]

I have the same car and Same problem. When the fan stops the a/c blows warm air. And some times the rpm drops so the car revs to a higher rpm. I did go to a fault reader shop and they gave me these codes.
GEM/SJB (Generic Electronic Module/Smart Junction Box) 1 problem exist


1.B2872-EO Tire Pressure Sensor Error


PCM (Powertrain Control Module) 9 problems exist

1. P0135-FF HO2SHTR11 Heater Circuit Error
2. P0141-FF HO2SHTR12 Heater Circuit
3. P0155-FF HO2SHTR21 Heater Circuit Error
4. P0161-FF Ho2Shtr22 Heater Circuit Fault
5. P0403-FF EGR (Exhaust Gas Recirculation) Valve Position Control Circuit
6. P0443-FF Purge Valve Circuit Malfunction
7. P0480-FF Cooling Fan #1 Control Circuit Fault
8. P0620-FF Generator Control Circuit
9. P0645-FF Air Conditioning Clutch Relay Circuit Error

The guy at the shop says it’s the computer. He showed me by putting water on it the compressor worked. At this point I don’t know what to do.

 

[Robert Larimer]

I have the same car and Same problem. When the fan stops the a/c blows warm air. And some times the rpm drops so the car revs to a higher rpm. I did go to a fault reader shop and they gave me these codes.
GEM/SJB (Generic Electronic Module/Smart Junction Box) 1 problem exist


1.B2872-EO Tire Pressure Sensor Error


PCM (Powertrain Control Module) 9 problems exist

1. P0135-FF HO2SHTR11 Heater Circuit Error
2. P0141-FF HO2SHTR12 Heater Circuit
3. P0155-FF HO2SHTR21 Heater Circuit Error
4. P0161-FF Ho2Shtr22 Heater Circuit Fault
5. P0403-FF EGR (Exhaust Gas Recirculation) Valve Position Control Circuit
6. P0443-FF Purge Valve Circuit Malfunction
7. P0480-FF Cooling Fan #1 Control Circuit Fault
8. P0620-FF Generator Control Circuit
9. P0645-FF Air Conditioning Clutch Relay Circuit Error

The guy at the shop says it’s the computer. He showed me by putting water on it the compressor worked. At this point I don’t know what to do.

If you clear all those codes do they come right back? What did the water do?

 

[Samikanaan]

If you clear all those codes do they come right back? What did the water do?

I only scanned the car 2 times. The 2nd time came more codes.

 

[Robert Larimer]

I only scanned the car 2 times. The 2nd time came more codes.

Did you clear your codes the first time? Most of the codes seem to have to do with wires. Have you looked over your wiring and fuse blocks for damage? The fuse block under the hood can get damage from overheating wires feeding the fan circuit.

 

[jukkitoly998]

likewise me also i'm having the same issue