Hello ya'll. I'm new to the forum and got a problem with my 2013 F150 (50K miles) EconoBoost pickup. Over the last couple of weeks the AC cools nicely from low to medium fan speed, but on high (or max AC) the AC only runs for 5 or so seconds then drops out. Turning system off for a minute or so, going back to low to medium speed it cools nicely. Could low freon cause this problem? AC has never been worked on, I purchased new April, 2013.

Thanks for any suggestions and guidance,
Ken H>

 

Welcome.

 

If it cools fine on low and medium speed, I don't think low freon is the issue. It sounds like the blower motor resistor may need to be replaced. It may not be as simple as that though. Stand by for other far more knowledgeable folks to chip in.

https://www.rockauto.com/en/catalog/...+resistor,6557

 

I sure was hoping it would be as simple as low freon. I'll wait for a few other replies, but resistor looks pretty easy. Only $20 plus shipping and looks easy to plug in without heavy wiring. Thanks for the responses

 

suggest clarifying what “drops out”: does the fan stop or change speed OR do you mean the temperature changes (cold air drop out)?

Also, when a resistor starts to fail you generally lose the lower speeds (and still have high), not the other way around.

 

Well Folks, this is embarrassing. I went to truck and did a decent check, temp of discharge air, at what point the AC "drops out", etc. I think the problem was "operator error". It seems the temp had gotten moved up a bit and when on high it would hit that temp quickly and turn off as it should. I turned the temp to LO on both side, moved the fan up to mid range where discharge air was around 60°F (ambient temp around 90°F outside). Moved fan up to next to max, discharge air dropped to 50°F. Moved to max fan speed, discharge air dropped to 42°F. Drove down the block and back with AC working just fine.

I do hope this is "problem solved". I wish to offer ya'll a great big THANK YOU for the comments and getting me to think a bit more on the problem and do some actual testing. I don't have the connector to use my gauges to test low pressure. With outside temp in the 90°F range seems the low side pressure should be in the 50 PSI range.

Thank ya'll again for the help.
Ken H>

 

OK, time for an update on the continuing AC saga. I thought the issue was operator error and was solved. That seems not to be the case. The problem is still happening. I got adapters for my set of manifold gauges so I could connect them. It has been so many years since I used them (40?) I had to do some YouTube research to refresh my knowledge, and for new knowledge about R134a refrigerant. Back then R12 was still in use.

I came to suspect the evaporator condensate line was clogged since it didn’t seem like any water was puddling below truck after running AC. I used 120 PSI air pressure in a hose stuffed into the condensate drain outlet –yea, the one hidden behind the engine on passenger side and hard to access. I wasn’t sure it did any good, but now after running AC to check pressures for 5 minutes or so I can see water draining from drain outlet. I suspect that the evaporator could use a good cleaning as it's 10 yrs old with around 50K on truck. Maybe the cabin air filter also could use changing? Do I understand the dash has to be removed to do a good job of cleaning the evaporator?

After cleaning the condensate drain, with the system running and temp/compressor set to Lo and fan in mid range the pressures tend to be 40 to 43 psi and around 190 psi on the high side with engine idling. Rev’ing engine up to 2,000 rpm will cause the low side pressure to drop to 25 psi range for a bit, then raise up. The high side will peak around 225 psi. This is with ambient temps in the 90 to 95°F range outside with humidity around 50% range so it really seems like the pressures are OK.

I drove the truck about 15 minutes or so, stopped a few minutes, came home with AC working good all the way. Hopefully the problem is now solved - until the evaporator 'n drain act up again. If anybody has an idea on how to easy clean the evaporator in this 2013 F150 I'd sure like to hear about it

Again, Thanks to all ya'll for comments and suggestions. It really helped me focus and do proper trouble shooting.

Ken H>

 

Probably no cabin air filter.

Your refrigerant pressures are excellent, no issue there.

You can purchase evaporator cleaner that foams up and does a fair job at removing dust etc from the evaporator core. Suggest dropping the blower motor and doing a visual of the surface of the core first. You may need a bore-scope for a good exam.