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1993 Seville
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7 Posts
Discussion Starter #1
Hey y'all. I'll make this quick. I live in Tennessee. Bought this ol girl over the summer. Runs great, sad to find out that it has no heat, it just blows straight cold air. I have seen the thread on how to flush the core, BUT. Before I do all of that. My coolant in the res is much below cold, in the cold. Will that cause this issue? And do I need to flush the coolant before adding more? I was told by the owner if I was going to add coolant use the NEW COOLANT. Note - this fella is about 85 years old and I had no.clue what in the world he meant by that. It's a 4.9 V8 non northstar. Thanks for y'alls time!
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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67,188 Posts
You can use any sort of name brand automobile coolant, mixed 50/50 with clean water, that floats your boat - just religiously change it every 3 - 4 years.

Your car does not have a "surge tank" pressurized to system pressure and receiving constant purge flow from the system - it uses a coolant expansion tank, unpressurized, not heated by any flow, and it will be cold when the ambient temp is cold. It might warm to something like underhood temps in slow, heavy traffic = no airflow through the engine compartment.

Feel the heater inlet and outlet piping at the firewall - it should be hot when the system is at operating temp. If it's not you have a clogged heater core; if both pipes are hot you have air blend door problems in the HVAC stack.

Note: This fella is 80 years old and knows EXACTLY what he is talking about.

Welcome to CF !!!
 

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70 Deville 78 Seville 92 Deville 03 Deville
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682 Posts
There is a plastic tee at the back of the engine near the heater core. It's called a heater valve at the parts store. I guess if that is intalled backwards you won't get any heat. I never understood that but there used to be a lot of threads about it. Feel all your hoses like sub said and see what is getting warm and what isn't.
 

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1993 Seville
Joined
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7 Posts
Discussion Starter #4
You can use any sort of name brand automobile coolant, mixed 50/50 with clean water, that floats your boat - just religiously change it every 3 - 4 years.

Your car does not have a "surge tank" pressurized to system pressure and receiving constant purge flow from the system - it uses a coolant expansion tank, unpressurized, not heated by any flow, and it will be cold when the ambient temp is cold. It might warm to something like underhood temps in slow, heavy traffic = no airflow through the engine compartment.

Feel the heater inlet and outlet piping at the firewall - it should be hot when the system is at operating temp. If it's not you have a clogged heater core; if both pipes are hot you have air blend door problems in the HVAC stack.

Note: This fella is 80 years old and knows EXACTLY what he is talking about.

Welcome to CF !!!
Thank you sir, I will get right on that. Can't feel my hands but bbn if those hoses are hot they'll warm em up 😂😂
 

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1993 Seville
Joined
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7 Posts
Discussion Starter #5
You can use any sort of name brand automobile coolant, mixed 50/50 with clean water, that floats your boat - just religiously change it every 3 - 4 years.

Your car does not have a "surge tank" pressurized to system pressure and receiving constant purge flow from the system - it uses a coolant expansion tank, unpressurized, not heated by any flow, and it will be cold when the ambient temp is cold. It might warm to something like underhood temps in slow, heavy traffic = no airflow through the engine compartment.

Feel the heater inlet and outlet piping at the firewall - it should be hot when the system is at operating temp. If it's not you have a clogged heater core; if both pipes are hot you have air blend door problems in the HVAC stack.

Note: This fella is 80 years old and knows EXACTLY what he is talking about.

Welcome to CF !!!
574604
so the hoses are hot. So I'm not clogged?
 

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1993 DeVille
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168 Posts
Yes .........If all are hot after car warms up then its time to check the air temp door accuator:
574633
 

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70 Deville 78 Seville 92 Deville 03 Deville
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682 Posts
Those hoses in the pic may be the feed hoses. I'm not sure if the outlet is located down below. I think that hose that runs below the crank pulley is a heater hose, probably the return. I don't know if the Seville is different. I originally thought this was a Deville.
 

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1993 Seville
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7 Posts
Discussion Starter #9
574646
so, with the heat on 90 it's in that position and when I turn it down around 60 it pulls back, but it may not actually be working eh? I hope it's just that haha I took everything down and looked at the core. Didn't seem bad so I put it back together
 

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1993 DeVille
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168 Posts
If your accuators are moving and no air pocket/low coolant bad thermostat
then I would say the heater core is plugged prob. with the GM sealant tabs added over the years.
I went thru this no/little heat issue in a 93 Deville I bought in Fla. last year.
Replaced core and plenty of heat now!
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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67,188 Posts
The "comes out warm and then goes cold" points to a partially clogged heater core. To flush that out will be a royal pain - you need to make up garden hose adapters for the core hot/cold lines and then carefully start flushing, slowly at first, increasing flow as the gunk starts to flow out. Flush forwards and backwards.

DO NOT install the discontinued coolant supplement tablets. GM stopped that in 2006 or so and none of the manuals or stickers were ever updated.

The "tablets" were either Bar's Leaks HDC or Bar's Leaks powder G12BP. There is a specific GM TSB on their discontinuance for normal cooling system maintenance.

Here's an old reference from the 2002 Seville (Northstar) service manuals. The ONLY way owners would know of the supplement tablet deletion change is to get the info in here (CF) or from a caring dealership tech or service manager.

cooling system supplement.JPG
 

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1993 DeVille
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168 Posts
DAD..........Do you note if that "tee" in the 3 water line connection is new or old? I note in some other no heat threads is the "tee" is not installed correctly.
 

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1993 Seville
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7 Posts
Discussion Starter #13
Its older. I believe it's the original one. I got a guy coming today to help me do a flush and we'll see if that's the issue. It doesn't look to be in bad conditions
DAD..........Do you note if that "tee" in the 3 water line connection is new or old? I note in some other no heat threads is the "tee" is not installed correctly.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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67,188 Posts
Yep - original metering Tee. Those are the assembly line original spring hose clamps.
 

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91 Fltwd Coupe (93 Regal Coupe & 90 LSC SE)
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394 Posts
My car isn't near me right now to check but did they have a vacuum controlled heater control valve this early? If so one can sometimes get heat by pressing in and out this valve several times quickly to dislodge any debris. The heater core may also need to be flushed. Also if the coolant is low there will be no hot coolant getting to the heater core.

While we're posting pictures, where exactly is the blower motor resistor located? Am quite sure mine needs to be replaced. I'm not driving mine right now as I found a loaded '93 Regal Limited coupe with the venerable Series I 3800.
 

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1993 DeVille
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168 Posts
Daddy.....Heres where I hooked up to flush my core in my 93 Deville.
(not my pics)
It didnt work as I still had little heat after flushing so I replaced the core.
The flush is worth a shot tho.
 

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1993 Seville
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7 Posts
Discussion Starter #18
So I did the flush. I had to go under the car at the car to the metal part of the overflow. So I back flushed, no heat. Found out it was the t stat. But I'm glad I flushed it. It was gross. I'm going to upload a small updated guide for people with this exactly model because that was a paiiinnnnnn. Thank you gentlemen so much!!!
 
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