Plugged heater core..

[The Fred]

Well the heater on my 1990 Seville doesn't work now.. rrrrr

It just throws out cold air,

The heater itself seems to be working it cuts off the compressor and changes to the floor vents

So I have a plugged core on my hands, right,

The heater use to work real well.. I think I put too many of those darned tabs in it

Will flushing it out with a garden hose do the trick.. I don't have many other options...

The defroster throws the same chilly air but the compressor comes on so it clears the windshield.. I've tried every setting including econ.

On some of my cads when I had a heater problem they would work on ECON setting..

[Kodiak]

Although I've never backflushed a Caddy, I have several of my cars and those of others as an "old ways" mechanic once taught me, they're either plugged or they leak. Assuming your antifreeze is at level, and no air trapped in the system, next cheapest test is backflushing. It has worked for me several times. Beyond that a blend-door problem could be an issue. I'm new to Caddy's so... Just my opinion. Good luck!

Doug

[BodybyFisher]

Agreed, first check coolant level, low coolant will provide poor heat. Secondly flush heater core in both directions after removing hoses. Be careful NOT to damage heater core stubs by being too rough detaching hoses.

[The Fred]

Yea the radiator it was a little low I topped it off and it didn't help,

How does one go about bleeding air from the system?

Let it run with the radiator cap off?

I'll go out this morning and run it up to temp with the cap off

And I'll check the temp of the inlet and return hose from the core

[BodybyFisher]

Typically assuming your cap is functioning and that its the correct cap, a couple of warm up cooling cycles will pull in coolant and expel air.

I recall it said that when you do cooling system work, to race the engine a couple of times to 2000 rpm but I have never had to do that.

Never run with the cap off, it could spontaineously boil.

[The Fred]

I've run cars with the cap off to get rid of air before..

What is this spontaneous boiling thing?

That sounds dangerous

[BodybyFisher]

Running with the cap off does not expel air, the warm up to normal operating temp and cooling cycle does that. Slowly fill the radiator to top and wait for bubbles to stop, put cap on, run a couple of cycles and you should be fine. The CAP has to be functional and the CORRECT cap. The correct cap has a poppet valve in the middle that is spring loaded, it should spring back up when you pull it down gently. It is a one way valve of sorts.

Spontaineous boiling occurs with the cap off when the coolant reaches boiling temp. Obviously you know that the lower the system pressure the lower the temp that the coolant will boil at... The cap raises the system pressure and therefore raises the boiling point.. I have seen radiators with the cap off puke out coolant all over the side of the car.

[PAUL T]

I just flushed my heater core out. It is easy once you get your hoses off. It took me about 1-1/2 hours to get the hoses off, with a few cut and bruised nuckles, and probably 15 minutes to flush. I followed the hoses out of the heater core and took them off beside the surge tank, much easier to get to. I had to fabricate a hook to break the seal at the end of the hoses in order to get them off. I spliced a length of garden hose to the end of one side and put the sprayer in the other then vice versa. I had some crud that came out and kept flushing until it was clean both ways.

Make sure the surge tank is full and the concentration is 50/50.

[The Fred]

Well I tried to flush the core but it wouldn't let any water through it..

I finally got it to let a dribble of water go through it but that was in

(I disconnected the outlet hose and I also disconnected the inlet hose at the T and I connected the garden hose to the inlet hose by hand)

Then I reconnected the inlet hose, left the outlet hose off and started the motor... I couldn't see any water coming out of the core until it started steaming like all heck so there must be water coming out of it now - I can't see for all of the steam and it is difficult to tell if water dripping is coming from there

[Caddynut]

try backflushing the core the opposite direction of the coolant flow. That will force the clogs the other way.

[The Fred]

That is going to be a **** but I have to

[The Fred]

Is there a trick to this?

Argggg

[PAUL T]

I just used a hose splice fitting attached to a piece of garden hose and stuck that to the outlet hose, then put my water hose nozzle in the inlet hose and let her fly. Then to back flush it I switched hoses. Make sure the piece of garden hose is about 4' to 5' long so it is far enough away from the engine bay. Also my water hose nozzle was just big enough to slip inside the hoses to form a nice seal. My nozzle slipped out once and I got a little wet, so don't feel too bad.

[epricedright]

I need to flush my core as well. My driver's side floor vent blows cold, but the pass side is hot. Adallak suggested said that maybe my core was clogged on that side. Anyone have any idea how much coolant there is in the core and heater hoses? Trying to figure out how much straight anti-freeze to add after I'm done to keep it close to 50/50. I just changed my coolant this summer.

[The Fred]

Getting to the hoses is a ***** ! heh!

[The Fred]

Well I managed to get the core unclogged.. it flows real fine now.

The inlet hose to the core gets HOT now ALL THE WAY to the core

(Before it only got warm and not all the way to the core)

I still don't have heat but I have "not chilly air" instead of cold cold air.. it's not warm at all just less cold.

Does it have to settle down and go through a few warmup cycles to get rid of air or what?

[Ranger]

You didn't completely remove the "T" fitting did you? One leg has a restrictor and must be in the proper leg. If not, check the coolant level again after it cools down and top off as needed. Then start it up again. Check it again after cool down til the coolant level stabilizes.

[KHE]

I need to flush my core as well. My driver's side floor vent blows cold, but the pass side is hot. Adallak suggested said that maybe my core was clogged on that side. Anyone have any idea how much coolant there is in the core and heater hoses? Trying to figure out how much straight anti-freeze to add after I'm done to keep it close to 50/50. I just changed my coolant this summer.

You can collect the coolant when you remove the hose and measure it to determine the quantity or you can use compressed air to blow out all the flush water and then top off with 50/50 mixed coolant. If the heater hoses are not in a convenient location that you can use a container to catch the coolant, drain a gallon out from the radiator and then the coolant in the heater core will drain into the radiator.

[The Fred]

You didn't completely remove the "T" fitting did you? One leg has a restrictor and must be in the proper leg. If not, check the coolant level again after it cools down and top off as needed. Then start it up again. Check it again after cool down til the coolant level stabilizes.

I took the hose that goes to the core from the T off and hooked it to the hose to flush the core then I put it back where it was...

Since the hose is HOT all the way to the core inlet now.. I think there is a blockage in the outlet hose. The core flows water real well now..

Also SIGH

[epricedright]

I need to flush my core as well. My driver's side floor vent blows cold, but the pass side is hot. Adallak suggested said that maybe my core was clogged on that side. Anyone have any idea how much coolant there is in the core and heater hoses? Trying to figure out how much straight anti-freeze to add after I'm done to keep it close to 50/50. I just changed my coolant this summer.

You can collect the coolant when you remove the hose and measure it to determine the quantity or you can use compressed air to blow out all the flush water and then top off with 50/50 mixed coolant. If the heater hoses are not in a convenient location that you can use a container to catch the coolant, drain a gallon out from the radiator and then the coolant in the heater core will drain into the radiator.

Thanks Kevin! I was thinking the same thing, blow out the flush water with compressed air when done and top off with 50/50. But I wasn't sure if that would work...would all or most of the water blow out you think? I guess it would if I can get to that outlet hose that connects to the engine on the passenger side that is accessible through the right front wheel well. I hear the hoses at the firewall are a bear to get to and/or get loose.

Well I managed to get the core unclogged.. it flows real fine now.

The inlet hose to the core gets HOT now ALL THE WAY to the core

(Before it only got warm and not all the way to the core)

I still don't have heat but I have "not chilly air" instead of cold cold air.. it's not warm at all just less cold.

Does it have to settle down and go through a few warmup cycles to get rid of air or what?

Fred, were you able to get your heater outlet hose loose at the firewall? The inlet hose is at the "T", correct? If not, I think the outlet hose where it connects to the engine on the passenger side might be easier...possibly? Adallak suggested it's easier to access that hose from the wheel well. If you haven't backflushed through the outlet hose, then there may still be crud in your core that is restricting coolant flow.

[Fretbuzz470]

easy way to check if your blend door is stuck open or not closing all the way and causing your no heat problem is to (once engine is at operating temp) take some sheets of paper and place them across your ouside air vents (usually under the hood just below the wipers) blocking the outside air from being able to enter and cool off your vent temp. If your vent temp goes up and heats well then you know you have some dash digging to get into. Otherwise if that doesnt work see if you can check the inlet and outlet temps on the core hoses. if there is a significant difference in temp you still have a blocked core.

[The Fred]

Yes the inlet hose to the core is HOT now.. before it was just warm.

The outlet hose is just barely a little bit lukewarm

I didn't know the core could still be blocked after I flushed it one way.

What a bummer!

[BodybyFisher]

Yes the inlet hose to the core is HOT now.. before it was just warm.

The outlet hose is just barely a little bit lukewarm

I didn't know the core could still be blocked after I flushed it one way.

What a bummer!

1) it is important to make sure that the coolant level is up 100% with no air in the system

2) that T has a SPECIFIC orientation and must be in that orientation (ranger noted this)

It appears you don't have a clog in your core, but now it appears your coolant leve is low. Check the CAP for proper operation if the poppet valve is hanging replace the cap

OUTLET hoses DO NOT get blocked

[The Fred]

I have the T just as it has always been.. and the heater use to work..

So I would imagine it is alright?

I'll pick up a cap in the morning, it seems to spring up and back down alright..

[BodybyFisher]

If the two hoses are NOT about the same temp, its either low coolant, air in system. If they are the same temp, your have an air mix door problem. Have you driven the car a few times to expel air and pull coolant in? When the car is COLD when you take the radiator cap off is the coolent to the TOP of the radiator near where the cap contacts, if NOT you are not getting the air out and pulling in coolant...

Check your thermostat, if its 180, change it to a 195 or spec (190?), I forget what the spec is.. Its also possible your stat is hanging OPEN.