93 Mint Buick Riviera - No Heat

Killaw4ttz

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Buick Ownership
93 Buick Riviera
15075


I just picked up this beauty today, only 111k miles and it's in almost mint condition, very well taken care of. Everything works fine with it....with the exception of the heater. The AC blows cold, all the vents seem to work. Turn it to heat, raise the desired temperature all the way to 90, only blows cold. So I was thinking it has to be some sort of valve to let hot coolant flow through the heater core, or it's the thermostat itself. The temp gauge sits one bar below half always, I don't know if that's the "normal" range, or if the thermostat is in fact stuck open and not allowing the car to get to operating temp....which would explain the lack of heat.

Any advice is appreciated, thank you.
 

MelsRegal

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Regal GS 2017
when cold is the coolant bottle at the proper level?
when the engine is fully warmed up does the upper radiator hose feel very warm to the touch?
the heater control valve would be located in one of the two heater core hoses. If it sticks closed no heat.
 

LARRY70GS

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Oakland Gardens, N.Y.
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98 Riviera, 70 GS455 Stg1
I just looked on www.rockauto.com and I don't see a heater control valve. The very first thing I would check is the ACTUAL level in the radiator. Even if the overflow tank shows the correct level, the radiator can still be low, and that can cause problems with heat. The other thing it might be is a temperature door inside the dash. Some cars use electric actuators to move the doors, other cars use vacuum to move the doors. That is something you need to research. If I was you, I'd be looking for a factory service manual. It is the second thing I buy after I purchase any car.

Having said that, I would jump all over this screaming deal on Ebay,

1993 Buick Riviera Factory Service Manual: CLEAN! (ALL Chassis-Body-Electricals) | eBay
 

2007LucerneCXL

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2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Here's some diagrams that may help. One item to check is the vacuum lines as they can become disconnected or crack, the other suggestions in above posts may help in troubleshooting the system.
1009164E09-001.png9203304E09-014.png920612GM09-008.png920612GM09-201.png
______________________________
 

Killaw4ttz

New member
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93 Buick Riviera
I just looked on www.rockauto.com and I don't see a heater control valve. The very first thing I would check is the ACTUAL level in the radiator. Even if the overflow tank shows the correct level, the radiator can still be low, and that can cause problems with heat. The other thing it might be is a temperature door inside the dash. Some cars use electric actuators to move the doors, other cars use vacuum to move the doors. That is something you need to research. If I was you, I'd be looking for a factory service manual. It is the second thing I buy after I purchase any car.

Having said that, I would jump all over this screaming deal on Ebay,

1993 Buick Riviera Factory Service Manual: CLEAN! (ALL Chassis-Body-Electricals) | eBay
Thank you for that link, that manual is on the way. I always try to get service manuals for every vehicle I own.

I filled the over flow tank to the proper level, I have not checked the radiator itself however. I'll check that today, though on the way home it had no problem keeping the temperatures under control.

It could definitely be a blend door, however I feel it might be closer to the radiator than that as there's no heat coming out ANY vents, not the top nor the bottom. Thank god I live in AZ and heat isn't something I need often and the AC works great.

Thank you for the diagrams, though I'm not really sure what I'm looking at. I'll take some pictures from underneath the hood, that might help.
 

Killaw4ttz

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Buick Ownership
93 Buick Riviera
1508515086


I checked the radiator, its full, and so is the overflow tank. I see the AC lines, but not where the heater lines run to the heater core.
 

HotZ28

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1996 Roadmaster Limited Collectors Edition 58k - 1996 PAU
I think you may be going up the wrong way, on a one way street! As previously mentioned, more than likely the electric blend door has failed, or the door is stuck closed, not allowing the actuator to open the door, which can cause the actuator to fail.
 
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