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2000 Mercury Grand Marquis 75,000 mi. A/C blowing hot and cold

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Apr 17, 2019, 11:26 PM

Post #1 of 4 (226 views)
2000 Mercury Grand Marquis 75,000 mi. A/C blowing hot and cold Sign In

My car's A/C blows good cold air, but will suddenly start blowing hot air. If I turn the A/C off and then back on, it will usually start blowing cold air again. I never know when this is going to happen. I took it to Firestone and they did an A/C test on it. They could not find anything wrong. It was suggested that perhaps the electronic control box (or something like that...I can't recall exact words and I'm not car savvy!) may need replacing. That would cost several hundred dollars they said. Things are extremely tight for me right now, but I really need the A/C here in Florida! Also, my Mom needs it b/c she has COPD and our front windows will no longer roll down. Any advice or suggestions would be appreciated. Also, I don't know if it is anything to do with the A/C or not, but the car often makes a clicking sound coming from under the dashboard. It sounds kind of like a piece of rubber is being hit by a fan going around. Wish I could explain better! It doesn't do it all the time, but quite frequently. Thanks so much!

Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 18, 2019, 1:47 AM

Post #2 of 4 (218 views)
Re: 2000 Mercury Grand Marquis 75,000 mi. A/C blowing hot and cold Sign In

OK. I think job 1 for you is to find the right place to take this on. The good news is you said it's able to blow cold air so a lot is ruled out. There are diverter doors that direct air flow thru the dash to deliver the assortment of air you request at dash can fail and make noise called "actuators" to be checked. There's more good news that it will fail for you regularly so should help the tech zoom in on the exact right fix that much faster.
Just being in Florida or a known warm area you should have a wide selection of places to go up to ones the specialize in this. Credentials include ASE certified A/C service is what I'd be looking for.

Lost in time myself Firestone is or was for tires and others like it take on more and more other things may be OK or maybe not really their thing fully?

Costs are generally pricey for A/C work there's just no guessing how much till it's known just what it is. Try to find the right place and get an estimate of the cost so at least you know. In writing what will be repaired or replaced actually could be something really simple to more involved just hasn't been convincing yet you have proper help or did and you just didn't understand the explanation of what it was. Did that person at the place give you a cost or some guess on the approach?

You aren't expected to know every detail or name of the item(s) in need just what you need to do and how much it will cost. If zero $ for this right now of course that's a problem it's not getting anything done over the web or this site - someone actually has to do it.

Have the estimate printed out and name what is found from that if you wish to understand it we could explain but right now not enough to go on,


Hammer Time
Ultimate Carjunky / Moderator
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Apr 18, 2019, 2:39 AM

Post #3 of 4 (215 views)
Re: 2000 Mercury Grand Marquis 75,000 mi. A/C blowing hot and cold Sign In

The fact that it resets when you turn the car off indicates that the AC system is likely setting a code and shutting itself down. That means with the right equipment you should be able to read the codes in the HVAC module. By "right equipment" I don't mean a generic code reader. You need a professional scan tool.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.


Apr 18, 2019, 9:19 AM

Post #4 of 4 (196 views)
Re: 2000 Mercury Grand Marquis 75,000 mi. A/C blowing hot and cold Sign In

Thank you so much for taking time out to answer my questions! It sounds like good sensible info to me from both of you and I will do as you say. I'll let you know what happens when I'm able to take the car in. Not sure when though! Thanks again!

(This post was edited by janetlee64 on Apr 18, 2019, 9:21 AM)

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