EATC O-ring issue??

[Fman]

Hey everyone...starting yesterday, I noticed that my heater was not working as expected. When I'm idling, the heat changes to cold, but when driving on the highway (higher RPM's), the heat starts coming, but not quite as hot as it should. I put the temp on 80 so it should be burning my foot. It seems to be coming out of the right places when I push defrost, floor, etc., but I only get heat when I'm on the accelerator. When I slow, the heat slowly changes to cold. I've read many of the EATC posts on this site, and many mention air only comes out of the defroster, but that's not my issue...maybe it's just starting to go bad?? Anyway, I'm looking for suggestions. Does anyone think replacing the O-rings is the way to go or could it be something else? I had the blend door replaced last year, so hoping it's not that. Never had any issues with the EATC in 111,000 miles. Thanks!

[fastblackmerc]

Hey everyone...starting yesterday, I noticed that my heater was not working as expected. When I'm idling, the heat changes to cold, but when driving on the highway (higher RPM's), the heat starts coming, but not quite as hot as it should. I put the temp on 80 so it should be burning my foot. It seems to be coming out of the right places when I push defrost, floor, etc., but I only get heat when I'm on the accelerator. When I slow, the heat slowly changes to cold. I've read many of the EATC posts on this site, and many mention air only comes out of the defroster, but that's not my issue...maybe it's just starting to go bad?? Anyway, I'm looking for suggestions. Does anyone think replacing the O-rings is the way to go or could it be something else? I had the blend door replaced last year, so hoping it's not that. Never had any issues with the EATC in 111,000 miles. Thanks!

It could be the o-rings, vacuum leak, air on cooling system or low coolant.

I'm leaning more towards the coolant being either low or air in the system since you get heat when you accelerate or a vacuum leak will give you the same symptom.

I'd check the coolant level first, then burp the cooling system, then check all the vacuum lines under the hood.

It probably won't hurt to replace the o-rings also.

[Fman]

I forgot to mention I did run the EATC diagnostic, but only received "888" so no codes.

[vegasmarauder]

O-rings only affect where the air comes out of. Blend door acuator affects the temperature, but since you got no codes I do not think the BDA is at fault. The last MM I had do this was low on coolant. I think when the dealer did the service they assumed it was full and did not check thru the cross over tube plug. Sometimes you can actually see the small change in the temperature guage needle going up and down, a good indicator of low coolant. By the way, it will eventually overheat when it gets a big enough air bubble.

[Fman]

Yes, I checked the antifreeze level and all looks good. I thought it couldn't hurt to change the O-rings anyway, but having trouble finding the right size. The one that was closest to original just barely allowed me to push the metal cylinder back in and it felt too tight to me, so I'm looking for smaller one with better fit. I went to dealer and they couldn't match the original. Is it reasonable to assume that a slightly larger o-ring that was tight fitting back in will not work properly? Thanks!

[RF Overlord]

The correct size is -007. Use a silicone o-ring.

[SamF]

Yes, I checked the antifreeze level and all looks good. I thought it couldn't hurt to change the O-rings anyway, but having trouble finding the right size. The one that was closest to original just barely allowed me to push the metal cylinder back in and it felt too tight to me, so I'm looking for smaller one with better fit. I went to dealer and they couldn't match the original. Is it reasonable to assume that a slightly larger o-ring that was tight fitting back in will not work properly? Thanks!

When you checked the coolant did you open the crossover tube service port when cold? Was there coolant at the port....?

[Fman]

FBM, I just sent you a PM. Thanks.

[wickedmerc]

I have a bunch of Viton O-rings left-over from when I changed mine. If you PM me your address, I'll send you some.

[fastblackmerc]

FBM, I just sent you a PM. Thanks.

I'll respond as soon as I get on my PC.

[Fman]

I was finally able to find the proper size O-rings and figure out my own inattention to the instructions (thanks NavySeabee) so was successful in changing all four, but during my test drive, I still have the same problem with heat...it pumps out the heat when I'm on the accelerator, but eases back with I'm cruising at low RPM's. This just started happening and was fine last week. The A/C works as I would expect. I ran the diagnostic again after I reinstalled the EATC and still no codes??

SamF, no, I've never taken that off before, but it looks like that's my next step. I need to have the antifreeze flushed anyway, so may see if that cures the heat problem.

wickedmerc, thanks for the offer, it seemed no one in San Antonio had ever heard of -007 O-rings. I finally found them at O'Reilly's, after visiting 3 of them.

[fastblackmerc]

I was finally able to find the proper size O-rings and figure out my own inattention to the instructions (thanks NavySeabee) so was successful in changing all four, but during my test drive, I still have the same problem with heat...it pumps out the heat when I'm on the accelerator, but eases back with I'm cruising at low RPM's. This just started happening and was fine last week. The A/C works as I would expect. I ran the diagnostic again after I reinstalled the EATC and still no codes??

SamF, no, I've never taken that off before, but it looks like that's my next step. I need to have the antifreeze flushed anyway, so may see if that cures the heat problem.

wickedmerc, thanks for the offer, it seemed no one in San Antonio had ever heard of -007 O-rings. I finally found them at O'Reilly's, after visiting 3 of them.

Just responded to your PM.

Does the heat come out just the defrost vents?

Here is the proper procedure to burp the cooling system. Unless your doing the work yourself I'd print these out and take them to whomever you get to change the coolant.... yes even the Ford dealer.

http://reischeperformance.com/refill.html

See my reply in post #2. The o-rings would have been the last thing I would have replaced.

BTW... unless you replaced the o-rings with silicone ones (usually orange colored) you'll be doing the repair again since rubber ones will dry up.

[NavySeabee]

Here is the proper procedure to burp the cooling system. Unless your doing the work yourself I'd print these out and take them to whomever you get to change the coolant.... yes even the Ford dealer.

http://reischeperformance.com/refill.html



^^^ A must! After taking mine to the shop for some work in the past, they didn't burp it correctly and I ended up overheating on the way home...about 2 miles!

[Fman]

Thanks for the tip; I'm printing it out now. I'm not doing myself, but having the antifreeze flushed tomorrow. I'm hoping that and the proper burping will clear up the problem.

[Fman]

For anyone who was wondering what caused my heater problem I discussed in #1, it turned out to be air in the coolant system, even though it looked like it was full. I told the service rep at the dealer that I suspected air in the system and he said "I've been doing this for 20 years and have never heard of that" and didn't believe that was the problem and suggested the heater core. I told him to do it anyway since it needed and sure enough, the heat is pumping out again, at idle and the rest of the time too:)

[RF Overlord]

I told the service rep at the dealer that I suspected air in the system and he said "I've been doing this for 20 years and have never heard of that" and didn't believe that was the problem Most dealer techs are unfamiliar with the DOHC coolant crossover so I'm not surprised he "never heard of that", even through there were plenty of other cars that had a specific coolant refill procedure to avoid an air bubble. :shake:

[fastblackmerc]

For anyone who was wondering what caused my heater problem I discussed in #1, it turned out to be air in the coolant system, even though it looked like it was full. I told the service rep at the dealer that I suspected air in the system and he said "I've been doing this for 20 years and have never heard of that" and didn't believe that was the problem and suggested the heater core. I told him to do it anyway since it needed and sure enough, the heat is pumping out again, at idle and the rest of the time too:)

Glad you got it working!