Heater blowing cold air....

91BLOWNSC

Registered User
Hey guys, the last couple of days after I start up my car in the morning the heat starts coming out warm after a bit. If i pull onto the street and accelerate kinda fast it goes right back to cold and won't come back to warm for another couple of minutes...up to 5 minutes. I play around with the climate control and shut it off and turn the temp down to 80 then back up to 90 but im not even sure if that is helping.
 
Sorry for the length..

91BLOWNSC


I hope I am wrong in this.. I am speaking of an experience I had with my 1993 Mercury Cougar 3.8 n/a... but I had that same effect on that car.. (before I totaled it) it was the Heads.. what was happening to me was coolant was passing into a cylinder.. and burning off... Coolant level was falling but no sign of a leak.. it was a slow process of losing it...

I would add coolant to bring it back up to level.. and still had the problem.. which this was caused by and Air Bubble in the system.. what I have seen work really slick is taking a radiator cap.. putting a hole in the center of it.. and mounting a funnel onto the cap, and sealing it... so it will not leak.. then put this contraption on instead of your good radiator cap... then run the car.. let it get to really good operating temp.. and you will see the coolant rise and fall... as it falls add some coolant... as it rises.. at times you will see the air bubbles come up.. just keep this up untill you see no more air bubbles...

close up the system again... and see if you have continuous heat... and if it ever happens again... and you don't see anything leaking... it may be burning off internally...

you can also take your car in and have the exhaust checked to see if coolant is being burned.. Might want to do this too.. to insure it is not a head gasket...

I most certainly would have never believed I had a head gasket problem.. till whammmm one day.. all coolant was gone instantly... and heads were warped so badly.. I needed the major work... then a week later.. it happeded to me again.. I ended up curing the problem by shelling out the 3200.00 for new long block and work done at a dealer.. the totaled it a year later.. Bummer huh...

Karl
 
How old is your thermostat? Put a new Ford one in. Try to stay away from aftermarket T-stats. I've seen to many of those stick closed on various occasions.
Other than that, make sure your cooling system is topped off with the proper mix of coolant:water.
 
well.

Thanks for the reply from both of you and I also have a comment to make. As for the radiator fluid I do beleive I am losing it because I add it to my resevoir quiet a bit and it always seems to disappear. But when I check the actual radiator it always seems full..as for the thermastat i had just replaced it probably a year ago with an aftermarket one. I replaced it when my water pump took a crap. My temperature gauge always show my car as cold but i think thats because my gauge is screwed up. Oh an another thing.....One thing I do notice all the time on my car is the smell of burnt coolant..I notice it, my dad does, and my friends. Only thing is I cannot figure out where its leaking if it even is. I get absolutley no puddles on the ground from coolant. Where can you get your car checked to see if its burning coolant? I have never heard of that being done before. Thanks guys!!
 
smell of burnt coolant

Check under the dash for a leak from the heater core. I agree with one of the other posts about getting a Ford T-Stat because they also have a weep hole and they twist into place. I'd toss on a new rad cap as well. good luck
 
Isn't it possible the problem could also be related to a vacuum leak? On the hard acceleration a leak could be closing the warm air damper and when the engine slows down and the vacuum lets off a bit it lets the damper open back up a little.

I'm probably just talking out of my ass, but that could be a problem too.

-Chris
 
Johnny_Squirrel

YOUR in MN... Cool.. Nice to meet you...

91BLOWNSC

As for getting your exhaust checked.. I had one of those Stealerships tell me that is what they did to prove to me it was a leaky head gasket.. So only assuming a Dealership could tell you with diagnostic equipment that your emissions is burning coolant as well... give one a call.. see if they know what you are talking about.. if no one does.. I will call the place that did mine.. and find out the technical terms of this test for ya

Karl
 
Watch out......

Mine did that last winter right before I blew the driverside headgasket! What happens is that there is a small leak between the collant passage and the #3 or #4 cylinder and the coolant is sucked in and burnt. The lack of coolant in the system is why you don't get warm air blowing out (no hot collant running thru the heater core).

Not to be a doomsdayer, but from what you described, that is what I believe is occuring. Do a compression check on your cylinders, as well as what the other guy said about having the exhaust tested for coolant residue. Any white smoke coming out after the car is warmed up? Your guage is probably showing cold because there is not enough coolant in the system to register a reading on the sending unit.

I may be wrong, but check it out. Good luck!
 
The radiator isn't the highest point in the sytem the heater core is. If you are low on coolant or have air in the system the heater core will get air locked (no coolant flow). Open the vent by the thermastat and fill the radiator until coolant comes out of the vent


My 90 Cougar LS would start blowing cold air about every three days. I would check the car and the heator hoses would be cold and the coolant tank would be overfull. I finally found the problem after fighting it all winter. The radiator had a leak about 1 inch from the top. The leak faced the a/c condensor and I couldn't see it very easy. What this did was leak out slowly under pressure. This caused the coolant to go low and air replace it. The overflow tank would keep filling up as coolant expanded, but instead of drawing coolant back into the system the radiator just drew in air. I used some aluminum seal as it was winter time and it fixed the leak, and I never had the problem again. I intended to replace the radiator but never did.
 
91BLOWN SC..

I Know exactly what your talking about as far as heat goes and burnt coolant smell, i just went through this and got it fixed
this is what the problem was
the return line from the rad was cracked and needed to be replaced so i did that.. still leaked, i got curious to the actual return tank so i ripped it out only to find the bottom post that sits in the frame to keep it in place was gone and a 3/16 hole was going straight down..
so i fixed that and it didnt leak as much
THEN i was toying around under the hood one day only to find the hose that comes off the Temperature sending unit to the heater core was rotted where ford puts the clamp around it, replaced that for 12 bucks and now i have NO problems
constant heat, no losing fluid anymore
its great
take a look bud trust me
 
aight...

Going to check a bunch of that **** tomorrow. Thanks for all the replies!!! Going to definitely get a new t-stat for now and keep and eye on that sucker. Its going to be stored here pretty soon so if something goes majorly wrong I would hope it would do it now so I can fix it over the winter rather than having it take a crap next spring. BTW does anyone store there car outside? I need some tips as to what things I should do to prepare it for outside storage.
 
Has anybody ever used "Fogging oil" before on an S/C? I've used it on small engines. It's a very light oil, in an aeresol can. You spray it down the engines air intake while running it until the tailpipes start to smoke, then shut the engine off. The idea here is to coat the valves and upper cylinder walls with oil to prevent rust. On the S/C you would probably have to remove a vacuum line from the inlet plenum and inject the fogging oil on there while it's running. Fogging oil burns easily, therefore, start up in the spring is easy to do and it won't foul plugs. The reason I picked this location is that if you pulled the intake pipe off and tried for the throttle body, you would be in trouble because the MASS air sensor is located at the air filter!
Before you put it away, when the gas tank is empty and you are at the gas station, add a bottle of STP Fuel Stabilizer, then completely fill the tank with premium. Make sure you drive it enough to get the new mix through the system and into the injectors etc. Stabilizer keeps the gas from turning into varnish.
 
update...

Well I bought a new t-stat and the gasket but I am now wondering that maybe its my radiator cap not sealing the radiator. Anyone have this trouble before or sound like it could be the problem? There was radiator fluid around the cap AND after it heats up it backs up into the overflow bottle. So thats why I was thinking it was that. Any ideas?
 
Yah, its a good possibility. Cooling systems don't work worth beans if they don't hold their pressure. Rad caps are cheap. I'd splurge on a Motorcraft though. I think I paid 12.00 for mine.
 
hmm..

Never mind...problem solved! It was the thermastat thank god!!! Woohoo no head gasket problems yet. 125,000 miles and still going :) I was worried. Anyways its all fixed now. The motorcraft T-stat seems to make my car run a little warmer like in the "o" of normal whereas the aftermarket one didn't even touch the "N" hmm...i wonder why. Anyways its all good now thanks for the help guys.
 
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