HVAC module diagnostic test

[smtas]

New member. 2010 explorer limited 4.6l. Gas dual controls. major a/c problem that has been worked on for several months. System replaced and compressor will engage and blow cold for about 10 minutes, then warms up. If you stop during that time, it will be warm on restart. Trying to get HVAC to do diagnostic test, but after pressing off + floor at same time, when I hit auto - fan starts.
Separately, even when a/c is blowing cold, scanner reads a/c command not allowed.
Over $2400 spent.

 

[JeffreyM]

New member. 2010 explorer limited 4.6l. Gas dual controls. major a/c problem that has been worked on for several months. System replaced and compressor will engage and blow cold for about 10 minutes, then warms up. If you stop during that time, it will be warm on restart. Trying to get HVAC to do diagnostic test, but after pressing off + floor at same time, when I hit auto - fan starts.
Separately, even when a/c is blowing cold, scanner reads a/c command not allowed.
Over $2400 spent.

For the 4th gen Explorer (maybe others as well);
"To enter the self test, press the OFF and DEFROST buttons simultaneously and release, then press the AUTO button within 2 seconds."
To exit the self test and retain all DTCs, press any button except DEFROST. The HVAC module —
DATC will exit the self test and retain all DTCs.
 Always exit the self test before powering the system down (system turned OFF). Once the self test is
exited, the ignition switch must remain ON for at least 30 seconds to allow the door actuators to
automatically recalibrate.

 

[smtas]

For the 4th gen Explorer (maybe others as well);
"To enter the self test, press the OFF and DEFROST buttons simultaneously and release, then press the AUTO button within 2 seconds."
To exit the self test and retain all DTCs, press any button except DEFROST. The HVAC module —
DATC will exit the self test and retain all DTCs.
 Always exit the self test before powering the system down (system turned OFF). Once the self test is
exited, the ignition switch must remain ON for at least 30 seconds to allow the door actuators to
automatically recalibrate.

 

[smtas]

Thanks. My understanding is that to run diagnostic the pattern is off + floor, then auto. Using defrost instead of floor, reboots HVAC.
The moment I hit auto, the fan starts and I get no diagnosis.
I want the diagnostic because a/c will run cold for 10 minutes upon start in morning, then turn to warm. Whole system has been replaced and no leaks. Mechanic is scratching his head and I am dying in Arizona heat.