For years now, my brothers F150 has way over cycled the fan with the AC on. I am A/C ignorant but I took some data with Forscan and hoping someone can guide us. I have the AC pressure, AC request, and Fan high command. Part way through I turn off the AC and then turn it back on. If there are other things to look at data I am missing, let me know!



The pressure seems to increase way too fast and the fan does its job to cool it off, but as soon as the fan is off the pressure is climbing fast again and so goes the cycle. The A/C works just fine otherwise, just annoying that the fan kicks on constantly.

I don't have a normal A/C system gauges, but was able to check the low side pressure independently. At 65 deg today, that was sitting right around 30 psi, which may be a bit high according to google? Any guidance is appreciated! Thank you!

If I understand what you're saying and it is a similar issue to what I'm experiencing, I haven't solved this yet on my 2016, but I *think* it relates to a non-Motorcraft thermostat. I bought one late last year and haven't had a chance to put it in yet.

Have you tried replacing the high pressure switch?

I haven't, looking for all suggestions. I guess I just need to rent or buy some gauges and see if the high side behavior matches the switch output. If gauge pressure is stable, and truck pressure switch output is still erratic, then is the switch.

If the high side gauge behavior does match the switch output, what would that be a symptom of?