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Discussion Starter #1
Okay guys need some help here. My 1995 Fleetwood, had zero heat this morning. First time I had tried the heat. I went and bought some flush and ran that all day as I drove around town. I got home and flushed it all out with a water hose. I blew out the heater core until the water was clear. Now here is the deal - I am not feeling much heat or really any flow from the hose that has the brass air fitting on it to the radiator. When I crack it open coolant does come out with no air - strange. The hose never gets hot. My heat will come on for a while, then goes away. The top heater core hose is not hot like the bottom one...so I assume the flow is not strong.
Could it be a thermostat? I ordered a new one just in case? Do you all think I still have air in the system? I will have heat for a bit, then hit auto and it redirects the heat elsewhere and it gets cold - or if I wait long enough it gets cold out of the defroster. I go outside and squeeze on some hoses and have heat for a while, then it stops.
Any clues?
Thanks!
 

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Discussion Starter #3
Okay,

Here is what I know. I have drained the system totally, flushed it all out. I flushed the heater core out via top and bottom hoses, back and forth until the flow was clear ad clean. THEN I ran air through it,back and forth. I hooked everything up, replaced the thermostat, replace the bleeder screw with one of those that has a valve on it with a hose so you don't soak the optispark. I bled the system many times. On and off. I had some heat. Turned the car off - started it back up, no heat! I went out turned the bleeder screw, line ran clear with antifreeze, no bubbles. I then squeezed the top heater hose all over, and the hose that comes out of the thermostat housing to the radiator ---- and I had HEAT! I bled the system, maybe one tiny bubble, but straight flow. Turned the car off, started it this morning ---- no heat. Did the squeeze trick, heat....

Is there is a control valve? What could I be missing? Also, the top heater hose stays coolish, not hot like the bottom one.

THANKS IN ADVANCE.
 

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Discussion Starter #4
Okay - I ordered these - did I cover the bases?


 

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2014 ELR
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There's no heater coolant control valves on LT1 cars. Here's what to do. Get the nose up in the air, ramps, hill, whatever. Bleed it again. Slightly overfill the reservoir. If you haven't done a new cap since you bought it, get a new one on there.
 

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96 Fleetwood, 94 Fleetwood, 07 CTS, & 94 Caprice Wgn
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What Jason said. One of those hoses has a "T" in it. The other is a a plastic reducer. Being over 20 years old, the "T" is prone to breaking. Like Jason, I've had these cars for 23 years, I've never had to replace those hoses, but I did have a "T" break. I would return the hoses, there not your problem.

Like Jason said, get the front up and bleed it. If I were to guess, your heater core is plugged solid. That's why one hose is hot, the other cold. I know you've flushed and the water came out clear. They are notorious problems. You may end up having to replace the heater core. Don't buy any parts until you know that's the issue.

Tom
 

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Discussion Starter #8
I can replace the heater core, I hate to do it, everyone I have done is been a big pain. I will try to get the car up in the air and bleed it that way.

If I am able to get the same flow our of each hose how can it be stopped up? Do the fins stop up and not allow heat exchange? I mean I am getting fluid though it solidly.

I have a shop manual - but any tips or tricks for replacing the heater core in one of these?
 

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96 Fleetwood, 94 Fleetwood, 07 CTS, & 94 Caprice Wgn
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If it's hot going in, and not hot or close to hot coming out, it's plugged. Possibility, as Jason said, it has an air block.

If it is the heater core, the first thing to do is take out the passenger seat and cover that area with a piece of cardboard. I have to give credit to Jason for that. He told me many years ago.

Tom
 

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Just asking but are you sure the water pump is working 100% OK and the belt for it ?

When Tstat was out did you test it to see it working OK? ( hot water on stove and see what temp it begins to open)

Could the dampers in the HVAC vents just not opening when it heat mode ?
If changing to defrost hows the air temp there ?

Another way to assure all air gets out
If you take Tstat out again

Heat it up with hot water in a pan on stove
When Tstat is open use a hard pill like a Advil and as Tstat is shutting when taken out of hot water let it close with the pill in the way so that stat cannot fully close

Now when adding water being Tstat is partly open then all air will purge out surge tank (have heater on high)

Pill will simply desolve and not hurt anything
 

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Discussion Starter #11
These are all great ideas! I am going to take the tstat out and try the pill trick, and also have the car up on some ramps, and see what happens then. I ordered a heater core, but I hate to start that job unless I have to do so. The water and air flowed so easy out of the hoses...I am just wondering if the check valve that is on the bottom hose, inlet I think, is stopping up. It is like a 20 dollar part online. ACDelco 15-5423 GM Original Equipment Heater Water Flow Control Valve with 5/8 in Bead

 

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You need to take a step back, figure out the issue, and stop buying parts that you don't need. That's not a check valve, it's a reducer.
 

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Discussion Starter #13
See that is what drives me nuts with GM, they call it a check valve but is just a reducer, good gracious. Well I can always return the parts if I don't need them. Today I'm going to elevate the girl and try bleeding the system again. If that doesn't work, tstat trick and bleed again. If that doesn't work.... then I will buy a space heater lmao. I guess I will be replacing a heater core if that all fails.
 

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Actually, it probably wouldn't be a bad to replace the reducer as it is prone to cracking. Maybe there is a check valve in it. Also some time replace the "T". Heater core can be a pain to replace, but not as bad as you would think. After doing it multiple times it becomes easier. The heater core is in the loop with those hoses. There are no valves. If one of the hoses is hot going into the core, the other coming out should be awful close to the same temperature.

If that's the original heater core, you're on borrowed time. I know guys have had to flush multiple times, to get some heat. Stick with it you'll get. I still think it's heater core related, but i've been known to be wrong on occasion.

How many miles on the old girl? It might not be a bad idea to put your location in your signature.

All else fails, move to Florida.

Tom
 

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I have 3 of these cars on the road now and have owned 5 of them.. They have all gave me heat problems. And by flushing the heater core always gave me heat. But not for long term, they always blocked up over time. I have changed the heater core in all of them. In the last one I flushed out then decided to change the core. then I had the new and old cores side by side. I blew through the old one, it was like blowing through a straw, the new one was like blowing through a 5/8" heater hose. Such a big difference I knew this is the problem.
 

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Discussion Starter #16
Silverfox103 - she has 119k on her clock. I am starting to suspect the heater core strongly. :( I put the queen on a hill tonight and did a bleed - a few bubbles came out but it was straight coolant after that - not any big bubbles. I think I need to start researching how to do a heater core in these cars...Ugh. I still do not get how I was getting strong and steady water from both sides of the core and this is an issue. The top hose is barely warm which tells me that its just not getting coolant. I just don't see how - the bottom hose is FIRE hot.
 

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Discussion Starter #17 (Edited)
The car heats up slowly, according to the dash it gets to about 176 and stays around there. I just tried to bleed it again, top heater core hose cold, no bubbles....guess its a heater core?
 

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You can do what you want, but didn't take long for me to figure out, this guy shouldn't be giving advice. That reducer is put in that line to reduce pressure and volume to the heater core. He is saying you don't need that, just put a 5/8 piece of pipe instead of reducer.
 

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Discussion Starter #20
You can do what you want, but didn't take long for me to figure out, this guy shouldn't be giving advice. That reducer is put in that line to reduce pressure and volume to the heater core. He is saying you don't need that, just put a 5/8 piece of pipe instead of reducer.
Agreed, I would rather be safe than sorry. I will replace the lines because I am in there anyway - but will replace the core - gulp.
 
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