a/c question thanks

[89 townie on 20`s]

sometimes when the townie is rollin down the highway with the a/c going it will go to hot for a minute. then blow out the top and botton for a min then go back to cold like noraml. any clue what might need replacing to fix it?

[nailfoot]

Is it at WOT that this occurs? The computer will usually switch the AC off at WOT, and if you have some vacuum issues, that would explain the direction change.

[Tman70]

Try this...

http://www.lincolnsonline.com/tech/00130.html

[Taran]

Welcome to LincolnsOnLine

1. lets see 20s bro! :D

yea it probably is vacuum...

[gadget73]

Yep, vacuum problems. Check the coffee can too. When the system loses vacuum, it defaults to hot defrost as a safety measure.

[joedogg]

Yep, vacuum problems. Check the coffee can too. When the system loses vacuum, it defaults to hot defrost as a safety measure.
I'm not doubting you, but what exactly is safe about it? Just curious.

[87 town]

sometimes when the townie is rollin down the highway with the a/c going it will go to hot for a minute. then blow out the top and botton for a min then go back to cold like noraml. any clue what might need replacing to fix it?
I guess there is a way to fix it but... I have had this same situation for years now and when asking mechanics and I think I had some agreement on line here to, that when you are pushing hard or maybe going up a hill or Wide open throttle that we are asking for "too much" power at that moment and the a/c condensor shuts down for that instant and when we back off on the throttle it will start again and all will be well.
I'm under the "assumption" this is normal! (but, I cold be wrong)...;)

[Dereck]

I'm not doubting you, but what exactly is safe about it? Just curious.

Hi Joedogg

It is so you can still defrost your windshield on a cold day, if it defaulted to "Floor" you would have nice warm feet but couldn't see where you were going :D

Regards

Dereck

[89 townie on 20`s]

what is WOT? also it never did it b4. check the coffee can for what? anything else i should check? so if ireplace all the vacum lines wood it make her run better.also it never did this when i stomped her b4 so thats why i wondering. when iy goed to hot it blows real hot for like 30secs, then back to normal. sre the vacum lines pretty much all the same size if so i will buy a shit load of it and change them all. im sure its never beenchanged . it only started this since i put the new ignition switch on . the one thta controls the blower and blinkers. so i hope that has nothing to do with it. also i will getr a pic in this weekend of my baby on those 20`s. ima tell she turns heads when we roll thru.

thanks.

[Ivan D.]

I guess there is a way to fix it but... I have had this same situation for years now and when asking mechanics and I think I had some agreement on line here to, that when you are pushing hard or maybe going up a hill or Wide open throttle that we are asking for "too much" power at that moment and the a/c condensor shuts down for that instant and when we back off on the throttle it will start again and all will be well.
I'm under the "assumption" this is normal! (but, I cold be wrong)...;)

Ya, it's normal, I'd hate to spin the A/C compressor on top of everything else when racing someone to that freeway exit :p

[89 townie on 20`s]

well i dont think its normal so when i change the lines ill let u know what happens. andwhere do i send the pic to?

[joedogg]

Hi Joedogg

It is so you can still defrost your windshield on a cold day, if it defaulted to "Floor" you would have nice warm feet but couldn't see where you were going :D

Regards

Dereck
ahh, there you go. That makes sense, thanks.

[gadget73]

The AC compressor cutout is normal, but having the air stream flip from hot to cold under light acceleration, and divert from dash vents to defrost is NOT normal. Thats a sign of a vacuum leak. The coffee can should be inspected for rust at the edges of the "lid" that could cause a leak. If in doubt, get a hand held vacuum pump and see if it holds vacuum. The check valve also needs to work, as does the thermal blower lockout. If there is a leak at the blower lockout, it will also cause issues with the heat/defrost, etc.

[Elemino]

The AC compressor cutout is normal, but having the air stream flip from hot to cold under light acceleration, and divert from dash vents to defrost is NOT normal. Thats a sign of a vacuum leak. The coffee can should be inspected for rust at the edges of the "lid" that could cause a leak. If in doubt, get a hand held vacuum pump and see if it holds vacuum. The check valve also needs to work, as does the thermal blower lockout. If there is a leak at the blower lockout, it will also cause issues with the heat/defrost, etc.Exactly the problem I have.

I learned something new recently though. In low, med, and high the air switches to hot under light acceleration, which sucks in Texas. However, if the "auto" mode (which doesn't work like it should) the a/c actually blows cold harder under acceleration... weirdest thing but I can live with it when the temps are only in the 80's and low 90's.

[87 town]

The AC compressor cutout is normal, but having the air stream flip from hot to cold under light acceleration, and divert from dash vents to defrost is NOT normal. Thats a sign of a vacuum leak. The coffee can should be inspected for rust at the edges of the "lid" that could cause a leak. If in doubt, get a hand held vacuum pump and see if it holds vacuum. The check valve also needs to work, as does the thermal blower lockout. If there is a leak at the blower lockout, it will also cause issues with the heat/defrost, etc.

If you need to do any sealing around the edges of the "coffee can" or have holes elsewhere on it I'll tell you what worked for me. Sand clean the seam or crack or hole area. Lay some bondo glaze compound or the likes into the area, sand it smooth and spray or brush on some high heat ceramic paint. Works well and will look decent when done.
My a/c cuts off for a few seconds on WOT, never 30 seconds, and then pops back on. I agree with gadget that you have another issue going on. The infamous "coffee can"...

[Elemino]

My a/c cuts off for a few seconds on WOT, never 30 seconds, and then pops back on. I agree with gadget that you have another issue going on. The infamous "coffee can"...I have that problem and my "coffee can" was just fine. I'd like to point out that just cutting off the compressor does not make the air turn hot... the air gradually warms up over about a minute or two. Ever turn your engine off and let the fan run on the a/c? Same deal. When it turns on it goes back to cool. Hot air is the result of the blend door switching over to heat. Now... how much money did Ford save by not making these things with servos?

[89 townie on 20`s]

ok i checked the coffee can its like brand new, theres 1 line coming off it that goes behind the dash i think, does it go to one of these check valve or the thermal bower thermal blower lockout, can some1 tell me where to look for these things ?

thanks

[Tman70]

http://www.lincolnsonline.com/tech/00104.html

http://www.lincolnsonline.com/tech/00130.html

[gadget73]

Hose from the can runs to the check valve, center of the firewall directly behind the upper intake manifold. The other line off the check valve vanishes into the dash to run the climate control head. This line has a T inside and comes back out as the blue line for the thermal blower lockout. If any of that leaks, the climate control goes really wacky. I'd suggest plugging off the lines for the TBL to see if it fixes the problem. Better yet would be to vacuum the system down and watch the guage to pinpoint leaks.

[Elemino]

This line has a T inside and comes back out as the blue line for the thermal blower lockout. If any of that leaks, the climate control goes really wacky. I'd suggest plugging off the lines for the TBL to see if it fixes the problem. Better yet would be to vacuum the system down and watch the guage to pinpoint leaks.Blue? I have never seen a blue line. Where is this? Also, so what you're saying is when the car is off you should be able to put it under vacuum? From where? I tried doing this from the line running to the can and it wouldn't hold a vacuum. Maybe I need to find a different place to try from?

[gadget73]

One line to the thermal blower lockout is blue, one is black. 90% sure the blue is vacuum, and the black goes to the outside air door motor, but I could be backward on that. Its also possible the colors changed at some point, but in 86 it was blue and black on the TBL. You should be able to pull a vacuum on the can itself with no other lines hooked up. If that holds, you should be able to pull vacuum on the line that connects to the can. It ought to hold vacuum if the check valve isn't leaking, and the thermal blower lockout is not leaking.

[NEAPNanny]

Having experienced this same fun with my 88 TC, I can sympathize. The interior temperature sensor is a calibrated vacuum leak, so you'll never get the AC control system to "hold" a vacuum. However, the plastic vacuum lines under the hood are notorious for becoming brittle with age. I found my supply line to the AC control head had cracked where it went through the firewall to the interior as well as the line to the thermal lockout. It started out as switching to full heat/defrost at wide open throttle, but progressed to wild temperature and vent swings at the slightest tap on the accelerator. I patched the lines with a short piece of rubber tubing (I know I should have replaced the whole length), but that took care of the problem.

[gadget73]

Quite true, it will leak down slowly but it should not drop off rapidly. There is a given figure in the service manual for checking the system, that it can't loose more than a certain number of inches of vacuum in a given amount of time, but I don't have the book handy. I want to say its 1 inch per minute. If there is a massive leak somewhere, it'll drop 15+ inches in a minute.

[zogltc]

My dad had teh same issue on his 83 Town Car...it wound up being the coffee-can vacuum resevoir under the hood. From years of condensation, it developed a small hole in the bottom, and would not hold vacuum. Got one from a junk yard for $5, and the A/C worked perfect....pretty simple fix...

[89 townie on 20`s]

although this is not on my townie its on my crown vic. it has a water leak right behind the alt and is dripping out of the block. can some1 tell me wtf this is and how to fix it. i hope it is not the block has a crack in it b/c it looks like where it has a gaket or something. it is a steady drip