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AC stops working well after hour on road

AC works fine to and from work (25 min drive). Took a trip the other day (2 hrs) and noticed about half way there that AC wasn’t cooling well. Temp on engine was normal. Turned fan up to high and didn’t get good air flow but you could hear the air… just not feel it, nor was temp as cool as I set it. 85-90 degree day outside. Let car sit for 5 hrs at destination, got in to go home, AC works fine. Half way (or so) home AC lost efficiency again (not as badly). Acts as if vents are blocked when it runs poorly. HELP!!

Your evaporator is freezing up. It really shouldn’t do that, you should get it checked. Meanwhile, you can reduce the odds of it happening by turning the fan up (before it freezes) and setting the air to recycle or to max AC (depending on the year of your Grand Marquis and if it is manual or auto climate control).

it’s an auto climate but I have the max AC setting. So… I’m taking a trip on thursday, new jersey to michigan. What’s my chance of getting there without roasting in my car? THANK YOU for answering by the way… thank you very much

When it freezes up, turn the AC off for a few minutes, but continue to run the fan. This will thaw the evaporator and allow the AC to work again. Until it re-freezes.

When you get home, take the car to a shop specializing in automotive AC repair. They can fix it. There is a device attached to the evaporator that’s supposed to prevent freezing. Yours has probably stopped working.

thank you so much. I’ll do what you suggest.