I was told by the dealer that I have a bad Cylinder Head Temp Sensor. The CHT talks to the PCM, to back off cylinders, so the motor won't melt down if heat gets excessive.

Does anybody know if the A/C compressor is shut down during this?

The factory manual says nothing.

The temp gauge stopped working, as did the A/C Compressor (the fan and recirc, and A/C lights all work-just blowing hot air.

All knowledge is appreciated, as tomorrow morning I have to remove the intake manifold to get at and replace the CHT-so much for FORD having "a better way".

 

Did you get a MIL and any DTCs?

Was the engine operating in Failsafe Cooling mode? If so, the A/C system is disabled by the PCM software according to the PCED.



Steve

 

My livewire can read my DTC's for some reason, but I get an engine light.

The truck isn't overheating, and no cylinders are dropping. Is Failsafe cooling mode, a mode that has to be cleared in the computer?

I just put a brand-new CHT in this morning, and I still have no Temp Gauge,
A/C, the engine light is on, as well as the CHECK GAUGES in the display.

I had the battery disconnected for two hours, so the PCM is most likely reset.

 

Try using a dedicated scan tool. There's a fault in the system and the tuner isn't helping you any.

Steve

 

I here ya. I locked up my A/C Clutch in the meantime, so I can have air.

The two suspects are the cluster, and the PCM.

I had a fresh STOCK PCM File sent to me last week, which helped take the tuner out of the candidates.

 

Did you get this fixed yet?

 

No.

I think my cluster is the problem, since I can read temp for 5 seconds after starting, and also through my Livewire.

 

I need to write a conclusion to this problem, so here it is.

1. The motor was replaced by the dealer @ 36,000 miles, due to an out of spec crank.

2. They swapped the motor.
3. One month later, the A/C failed, and so did the temp gauge.
4. The dealer said replace the CHT. I Did. It still didn't work.
5. The dealer said I needed a new PCM.
6. I rigged the A/C Clutch to lock-up, to get air.
7. Multiple adjustments failed, and I had no air for two weeks.
8. I bought a Powertrain/Emissions manual to learn more.
9. I logged on to www.justask.com, and a 23-yr Ford Tech gave me a list of things to test, and he nailed it on the first step (Fault in the CHT Power lead). The motor swappers wrapped the CHT lead around a harness, and stressed the positive lead so hard it broke. I paid 15 dollars for the advice from Justask.com.
10. I fixed the fault.
11. I fragged the A/C Clutch from rigging it, so 2-day aired a new one from Tasca Ford.
12. I installed it, and had A/C.
13. Total Cost to fix. $125
14. Total recommended by dealer. $1250
15. One tenth, any questions?