A/C blowing hot air

2007 MERCURY MARQUIS
140,000 MILES • 4.8L • V8 • 2WD • AUTOMATIC
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BECKAG82
  • MEMBER
  • 1 POST
Had Freon put in and it was ice cold and stayed cold until I turned engine off for just a minute and it was blow dryer hot. as soon as I started it back so took it to garage they worked on it and it was ice cold again, but as soon as I shut the car off it was hot again.
Jul 22, 2021 at 8:25 PM
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KASEKENNY
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 18,907 POSTS
This is one of two issues. Either the compressor is not kicking on after a restart, or the blend door actuator is getting stuck at full hot.

Let's start with starting the vehicle and when it is blowing hot, open the hood and see if the compressor is engaging.

Here are a couple of guides that talk about both these issues:

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

https://www.2carpros.com/articles/replace-blend-door-motor

Once we know if the compressor is coming on or not we will have a better idea on what to check. However, I am going to suspect it is not so we need to check if the relay is sending power to turn the compressor on.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Below is the wiring diagram that will help with this. Basically we just to check the voltage at the compressor and I suspect you will not have any. If that is the case then it could be a relay issue or control module issue at that point but let's check all this and that will tell us what direction we need to go in.

Thanks
Jul 23, 2021 at 8:07 AM
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