89 GM... Brrr.... cold in the car, please help

[lithdoc]

Hello all,

I finally found a forum for the people that really love their panther cars. I recently got 89 grand marquis, and I must say that its a truly wonderful car to have.

Anyway, it seems that I can join the club of the miserably cold people here . My issue is that the car will never warm me up past some 40-50ish degrees inside. It will take it forever to give me some luke warm air, so it ain't fun. Yes, it is equipped with ATC.

I read the stickies here about possible vacuum leaks and air temperature sensor issues, but I failed to find a clear cut path to start the troubleshoot.

Please help. Thanks in advance!

[marquisman]

do you want a temp way to get heat? lol get a golf tee and plug the clear vac hose commin from the big brass round modulator behind the glove box. only thing is, it will be full heat all the time. reason being, is that you wont be able to control the blend door

[lithdoc]

Yeah, I'm going a little bit through a deja-vu here...

When I bought the car, it was summer. I remember looking around there, being frustrated not to be able to control A/C temps (it was too cold as well, but that time because of uncontrollable A/C), and seeing that hose plugged with a bolt. I was like, wtf - this obviously goes here - and I put those together... Thanks, I'll try that out.

Now, is it possible to actually fix it? If so, is it a big headache to do so? Thanks!

[sly]

you have to take the dash pad off. Then you'll find the ambient air temp sensor that the temp setting on the controls is tied to with a cable. You probably just need to replace that. Lots of screws and an $85 part. The one in my 82 Mark had died from internal rust (inside the sensor). Replaced it and everything worked fine. My 88 only had the problem with flooring the vents (check valve was bad).

as far as actually replacing it... it's 3 screws once you get the dash pad off. Not much trouble after the dash pad is removed. Be VERY CAREFUL with the screws in the defroster vents. You may even want to stuff rags in the vents to prevent dropping stuff down in them.

There are those 4 screws in the defrost vents... one screw on each end against the doors and 7 or 8 screws up under the front lip. Lift off gently and move out of the way. then the sensor (big blue thing with a hose out one side, vacuum lines out the other and a cable mounted on top) is pretty self explanatory.

[87gtVIC]

Just to help explain what was said about about the 4 screws part etc...slymer is telling you how to remove the dash pad.

The sensor is in a shitty spot and uses 7/32 bolts iirc. Not fun.

[87_crown_vic]

sounds like a blend door issue... if you can... remove the floor deflector and look into it from the driver side... you should be able to see the heater core thru there if using a flash light... if you have skinny arms like mine, you can reach in there and move the door open ... do this with car running so you know which way you are moving the door... if cold move other way to get heat...

[lithdoc]

sounds like a blend door issue... if you can... remove the floor deflector and look into it from the driver side... you should be able to see the heater core thru there if using a flash light... if you have skinny arms like mine, you can reach in there and move the door open ... do this with car running so you know which way you are moving the door... if cold move other way to get heat...

Is that a different than the plenum door that is present on the passenger's side? Because I can see the heater core from there, I think, but it only opens one way, and when pushed it immediately closes.

[gadget73]

the door you can access easily is the fresh / recirc air door. 95% of the time when these cars have temperature problems and its ATC, the interior temperature sensor failed. No heat is a bad sensor, no cold is usually the blend door motor unhooked because someone had no heat in the winter.

[lithdoc]

Okay, sensor it is! They're $75 on ebay, I'll pick one up. In the meantime before it comes, I will just try to plug the vacuum hose and hopefully I'll stay warm. Thanks for all your help guys.

[Tiggie]

I found my new ATC air temp sensor in a junkyard. Got it for $2. It's super easy to spot newer ones because they have the date code marked on them (this one had a 1997 date code). Just open the glove box and look up. My ATC works like magic now except I still have a bad check valve that gives me full on heat during low vacuum.

My old one was just full of dust. I'm going to try cleaning it to see if it'll work again.

[lithdoc]

Thanks for the tip. In the meantime, I just plugged up the vacuum tube, so it is warm for now. I wish I knew that when I was driving 80 miles per day last month!

I will now wait until january for my ebay bucks to kick in, so I can buy a new one now for ~60. Thanks guys!