Hey everyone. Looking for some help with an air conditioning issue the local dealer cannot figure out. When I go through a carwash, the ac compressor kicks off and the ac starts to blow warm air. I turn the AC off, and turn it back on, the compressor kicks on but runs for about a minute then turns off, and the check engine light comes on. The next morning I turn the ac on and everything is fine, and the check engine light will eventually cycle off. I am thinking something is getting wet that should not be, as this only happens when I go through the car wash, and not while driving in the rain. Any suggestions what I should check? I looked under the hood and only place I noticed some water was near both the headlights, everything else on top was dry.

Thanks---shawn

 

Just For Giggles Check your Cowl Drain. If it's Filling up in may cause A/C issues! Does noT Hurt to Look and when was the Last Time you Replaced your A/C Cabin Filter Anyway.

https://lmr.com/products/s197-mustan...water-leak-fix

KC

 

[QUOTE=05stangkc;7068887]Just For Giggles Check your Cowl Drain. If it's Filling up in may cause A/C issues! Does noT Hurt to Look and when was the Last Time you Replaced your A/C Cabin Filter Anyway.

https://lmr.com/products/s197-mustan...water-leak-fix

KC[/QUOTE

thanks for the tip, i will try it this weekend! I did change my cabin filter 3 months ago, was dry

 

What is the year and type is this Mustang.
2013-14 GT has hood vents that might let water spray down on a AC valve shorting it out, water shooting through the radiator could even get the belt or AC compressor clutch wet. Compressor kicking on causing the belt to slip causing the alternator to slow down could also kick on the check engine light.
Rain unless you are driving through a Monsoon barely gets the engine compartment wet. Car wash (Thinking Touchless) sprays high pressure directly at the grille, hood vents (if any) and straight down on the cowl so if the drain is plugged it could leak into the car (check passenger side carpet to see if it is damp).

 

Also make sure to check your drain plugs located on the bottom of the inner firewall.. If they become clogged, water will build up inside the firewall, then enter thru the cabin air filter and finally wind up leaking inside the passenger side compartment.. The passenger side drain plugs are located below the cabin air filter in the inner firewall.. The driver side drain plugs are also located on the bottom of the inner firewall, however, the removal of the driver's side windshield wiper arm assembly is also required...

 

If you're talking about the floppy rubber vent cap things that love to clog up with leaves and dirt on the cowl/firewall area, you're doing too much work! On my '12, and my bosses '10 and '14, I was able to reach back behind the motor towards the firewall and remove both of those rubber drains, without removing anything to gain access.

 

Yes! I'm referring to those floppy rubber vent cap things that clog up with leaves and dirt, just as you mentioned on the cowl/firewall section... From my understanding, there are also 2 more located inside the inner cowl/firewall area... The first is located below the cabin air filter, while the other is located inside of the driver's side inner cowl/firewall section...

 

Hmmmmmm....

Well, it sounds like I'll be checking things out in the cowl when I change my cabin filter. I was under the impression there were only 2! Down here in Florida, I'm taking every possible precaution I can against water leaks!

 

Hope there are only 2.. It would be much less of a PITA if those 2 are the only vent caps