Heater not working; confirm it's heater core or blend door first!

[spon]

I'm not a car expert, so I need feedback before i start replacing heater cores or blend door actuators...

A few months ago, it was night time so I turned slide the temperature control slider all the way to hot. then turn the fan on. To my dismay, after 5 minutes there was no hot air; only blowing cold air. (wife getting mad!). After about 10 minutes, the heat started blasting into the car.

Steadily it got worse and worse. Sliding the temperature from cold to hot, it would take 15 minutes. Then hot to cold, it would take 20 minutes. Now i"m just stuck at cold air. it feels like sometimes gets luke warm, but never hot like before.

Each time it doesn't work, I tried different buttons: Vent, Heater, Blend, Defrost. Each time the air seems to be directed to the correct spot, just not the correct temperature.

Is this the symptom of a heater core going out? or an actuator? or something else? I looked at replacing the core and the actuator, and it seems like alot of work. I want to make sure before I go and do it.

I have searched and looked at other posts, but I can't tell how some people determined its' the core or the actuator. if someone can clarify that it'd be great.

Thanks in advance.
Scott

 

[Spriteman]

What year and trim level is your car?

To check if it's the heater core - check the two hoses going from the engine bay into the cabin through the firewall.

They'll most likely be right in the middle of the firewall. One will be hot and you will not be able to keep your hand on it - that's the supply line. The other running right next to it will be the return line and will be slightly cooler but still warm enough to feel it.

If those are both hot/less hot then you probably don't have a clogged core - when it warms up in the spring you can back flush it with a garden hose putting the hose into the less hot and pushing it out the other side just to make sure it's nice and clean.

Also, have you checked to see if the heater core is leaking inside? Sometimes happens.

If the hoses feel okay then you may have a bad blend door(s) - one each for the driver and passenger side.

There are other posts that get into detail on checking the blend doors.

 

[scottydl]

The absolute first thing to check is your coolant level. If the coolant leaks out and level gets lower slowly, you'd have less heated fluid passing through the heater core which is what provides the hot air.

Secondly, what year is your LeSabre? If the "Engine" digital gauges show engine temperature, watch that measurement and see what the highest temp is that your engine is reaching. I believe the gauge is actually measuring the coolant temp and not the engine temp itself, but that could give a clue to what might be going on too.

 

[imidazol97]

If you car is a 1999 or older, the problem could be the blend door actuator. That's an electric motor that pulls a metal rod that moves a door to force air through the heater core to heat it up or lets more or less of the air bypass the heater for moderate temperatures. This actuator can have a gear inside crack and then slip on the hub that it's supposed to turn.

If it's 2000-2005 there is a different electric actuator that moves the door to blend the air temperature.

But first you have to be sure there is a full level of coolant in the radiator. When the car has cooled down for 30 minutes or so, take off the radiator cap by pushing down on it to turn past the catches. I recommend using a towel over the cap in case some coolant bubbles out under pressure. If that's not full to the cap level, then you may have a coolant leak internally in the engine or on the coolant lines at the elbows, plastic tubes that carry coolant to the heater hoses.

If there's low coolant, the heater core is the first to have air bubbles, and the air doesn't heat up the metal and the air inside the car.

If radiator is full, when the car has heated up after running, the upper radiator hose should start to be warm from coolant being let through. After the car has been idling or driven a short time and the temp gauge says warm you should start to feel the upper hose get hot as small amounts of hot coolant are put through it and eventually it warms up. After driving for while, the upper hose should be too hot to hold your hand on for more than a few seconds, unless your hands are toughened up from some kind of work.

But until the dial gauge or digital gage hits about 190, the upper hose should be relatively cool.

The two heater hoses should both be hot, one slightly cooler which is the outlet. If you turn off the heater inside, the one hose may be almost the same as the other one. But if you turn the blower on high and set the temperature to hot, the water should lose more heat to the air in the car, and the one hose will be noticeably cooler, but not cool. Sometimes having someone run the engine at 1500-2000, will help the cooler tube warm up from increasing the coolant flow through the heater. That would be normal.

 

[spon]

Hi all thanks for your input. I will check those items out this weekend.

To answer your question. I have a 2000 Buick LeSabre Custom. It has 80,000+ miles on it (I inherited it from my Grandfather, who didn't drive it much).

PS. I updated my profile to list the car too 🙂

 

[scottydl]

To answer your question. I have a 2000 Buick LeSabre Custom. It has 80,000+ miles on it (I inherited it from my Grandfather, who didn't drive it much).

Sounds like you pretty much have the same as I do. Except mine has twice as many miles!

 

[spon]

Okie Dokie, here's what I found:

RE: Coolant level. a few weeks ago I did fill the coolant to the cold engine marker. but I hadn't filled it in years (again low mileage). At cold engine, the coolant is at the cold engine marker. At hot, it is in the middle of "cold engine" and hot engine markers.

RE: Coolant temperature. I drove home and the coolant was hanging around 187degrees on the freeway. then when I got home (approx 20-25 minutes) it was fluctuating around 192-195. I did play with the heater around this time, which may result with the temperature flux.

Re: Radiator hose. when I got home I did a touch-test on the hose, it was hot. I didn't hold that hose for long. a few seconds.

Re: Heater Core Hoses in engine bay: both of these hoses were hot. they could have been at the same temperature.

Re: Heater core leak. I looked under the dashboard, where the vent is. there is no moisture there, nor does it look like any leak. I assume this is where the heater core would leak to, and I didn't find anything.

So based on the information that you provided me. it sounds like the blend door is malfunctioning. Would you agree?
If so then I am following the 2nd sticky thread to replace the blend door actuators?

 

[Spriteman]

I would say you're headed down the right track - although you may have to replace only one of the blend door actuators. If you do wind up replacing both you'll need two different part numbers as they are not interchangeable.

You need to get under the dash on both sides and after removing the hush panels look and see if you can tell if the actuators are moving. They should move all of the time - they are constantly adjusting the amount of open/close the doors are. They actually have 255 distinct positions they can be in - sort of like degrees on a compass.

Then, even if they are moving the white hub on the actuator they might not be totally locked in to the blend door linkage causing the door not to move. So, even if the motor is working it's not actually turning the door.

So, you have to determine the actual condition of the actuator on both sides. If one side is comfortable then that side is probably okay.

Also, you might try testing the fresh air inlet actuator by turning to Recirculation (Recirc) and see if that actuator is moving that door.

Another quick thing you can do before replacing an actuator is to put the actuators into a relearn mode. Turn the key on with no start and let it sit that way for 5 mins. When you do that the actuators will recalibrate and allow the computer to know for sure that the motor is fully open and fully closed and all of the points in between. That may have no effect on the problem but it's worth a shot just to make sure they are in the right positions.

That would also be a good time to see if the actuators are moving from underneath.

By the way - if you have a scanner you can see the actuator positions and I believe you can even command them to move to certain positions - that might give you another diagnosis tool.

 

[spon]

Ok. I feel like i'm a little over my head now. I bought Dorman 604-106 (Passenger) and Dorman 604-111 (Driver). I believe these are the right parts. (but by all means tell me if i'm wrong). One thing here is that they look like identical parts. they have the same body and same connector. One is marked 604-111 with the dorman logo. the other is not (I'm starting to question if it actually is Dorman)

I pull down a bunch of parts underneath the dash. and I found the one on the passenger side and the driver side. Both are against the middle of the dash.

One thing I did notice that concerned me. the two dorman products have power connectors with a pin missing. both are ooxooo (o being the pin and x being missing) However the ones that are currently installed have all the pins there (oooooo). does this mean that the ones I bought are wrong?

I hope I gave enough info to where I'm at. if anyone has any suggestions please let me know.
thanks.
Scott

 

[spon]

I can confirm that the "Driver side" actuator is a mode actuator. ie, it moves when changing from vent to heater to blend to defrost. So thats not it.

 

[Spriteman]

You have found the Mode actuator - you're seeing the white plastic linkage move when you command defrost, vent, heater, etc...

Look just a little more toward the firewall/engine bay and you should see another actuator that will look very similar to the other one - that will be the drivers side temp actuator.

In fact, I think you almost got a pic of it in your 2nd pic.

If you take off your glove box you'll be able to get to the passenger side more easily.


One more question - when you go to defrost mode do you feel a lot of heat on the windshield?


One way to verify the Dorman part numbers are to write down the GM P/N off of your actuators and just type those into Google - it will bring up all sorts of sites including Dorman's where you can see their part number.


You've done the hard part - now once you verify the P/N then actually installing the actuators isn't that hard - just a couple of hard to get to screws.

 

[Parksplace]

Take out the glove box. One screw for the cable door retainer. Two screws at the top. Yank firmly but gently as it is also held by three more small clips then carefully wiggle it out. Gives easy access to the part. Oh, and there is an electrical connector on the left side of the glove box for the light. I also bought the dorman part at a significant discount from Advance Auto, Dealnews.com got me the discount of 40 %. I had trouble putting it in because the dorman part wasn't set right. Took it to a dealer and he reset the gear and had it in in 10 min. Just something to lookout for.

 

[Parksplace]

Ok. I feel like i'm a little over my head now. I bought Dorman 604-106 (Passenger) and Dorman 604-111 (Driver). I believe these are the right parts. (but by all means tell me if i'm wrong). One thing here is that they look like identical parts. they have the same body and same connector. One is marked 604-111 with the dorman logo. the other is not (I'm starting to question if it actually is Dorman)

I pull down a bunch of parts underneath the dash. and I found the one on the passenger side and the driver side. Both are against the middle of the dash.

One thing I did notice that concerned me. the two dorman products have power connectors with a pin missing. both are ooxooo (o being the pin and x being missing) However the ones that are currently installed have all the pins there (oooooo). does this mean that the ones I bought are wrong?

I hope I gave enough info to where I'm at. if anyone has any suggestions please let me know.
thanks.
Scott

You have the wrong parts. You have manual temp control. The part you have is for auto temp control such as you would find in a Lesabre Limited or Park Avenue. Your part number 52474990 crosses to 89018377 (new part number). The Dorman part number you would need is 604-118. However, the Dorman part may need to be reset. To save the hassle, buy the ac delco part. When you look at the back of the part the white part needs to be set at the 12:00 position to install it. I just did this last week. If its heat your missing, you should just need this one part that is to the left of the glove box after you take it out. Once the glove box is out of the way, it is fairly easy to get to.

 

[spon]

You have found the Mode actuator - you're seeing the white plastic linkage move when you command defrost, vent, heater, etc...

Look just a little more toward the firewall/engine bay and you should see another actuator that will look very similar to the other one - that will be the drivers side temp actuator.

In fact, I think you almost got a pic of it in your 2nd pic.

If you take off your glove box you'll be able to get to the passenger side more easily.


One more question - when you go to defrost mode do you feel a lot of heat on the windshield?


One way to verify the Dorman part numbers are to write down the GM P/N off of your actuators and just type those into Google - it will bring up all sorts of sites including Dorman's where you can see their part number.


You've done the hard part - now once you verify the P/N then actually installing the actuators isn't that hard - just a couple of hard to get to screws.

To answer your question: there is no heat on the windshield. no heat at all. only cold air.

 

[spon]

You have the wrong parts. You have manual temp control. The part you have is for auto temp control such as you would find in a Lesabre Limited or Park Avenue. Your part number 52474990 crosses to 89018377 (new part number). The Dorman part number you would need is 604-118. However, the Dorman part may need to be reset. To save the hassle, buy the ac delco part. When you look at the back of the part the white part needs to be set at the 12:00 position to install it. I just did this last week. If its heat your missing, you should just need this one part that is to the left of the glove box after you take it out. Once the glove box is out of the way, it is fairly easy to get to.

Aww bleep. I had a bad feeling about that. Well I'll find the new parts. thanks for the info.

 

[spon]

Thank you everyone! I replaced the actuator identified by Parksplace (52474990) and now the heater is working again. I pulled out the glovebox and that gave me direct access to the actuator. after installing it, I watched it turn as I adjusted the temperature.

Now there is heat and cold blowing out. just in time for summer! lol.

 

[Spriteman]

But - no work for next winter and a good feeling that you've already tackled it and not having to get out in the sub-zero to fix it.