1997 Saturn SL1 Heater barely gets warm. Certainly not HOT

LOCASCIO

MEMBER
1997 SATURN SL1
4 CYL
FWD
MANUAL
170,000 MILES

Been having an issue with my saturn. The heat has slowly been getting cooler and cooler. Now that it is cold out, it hardly gets warm at all. I can get a little heat out of it if I am on the highway. The coolant is clean and full. This does not seem to be a blower or control problem either as they seem to function as they always have. Could this be a thermostat? I don't want to change it if it is not the issue as they are rather expensive. Does this care have a "heater control valve"? I am not familiar with these (was in the "what to check first" list). Any help would be appreciated! THANKS!

Monday, December 14th, 2009 AT 12:12 PM

4 Replies

MIKE H R

MECHANIC
3,094 POSTS

Check the temp guage when car has been running, It should be towards the middle of the guage. Some don't have temp guages so check the hoses to see if they are warm. What your post tells me is that the thermastat is probably stuck towards the open position. Letting the coolant circulate too fast to heat up. On the highway the car is using more energy and producing the little heat you are getting.

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Monday, December 14th, 2009 AT 1:51 PM

LOCASCIO

MEMBER
2 POSTS

So, I replaced the thermostat, didn't seem to make a difference (temp gage not even reaching half way). So here is what I am thinking? When I filled the coolant back up, it didn't seem to take as much as what came out. Maybe I have a water pump problem. After allowing the car to warm up a bit, I felt the hose going from the thermostat to the bottom of the radiator. It did not feel solid (like there was pressure) and it was not hot. Same thing with the hose going from the top of the radiator to the intake area (top of motor). Then I took the cap off the resevoir (I know I shouldn't have with the potential for pressure), but there was no pressure there either. Could there be air in the system, like a vapor lock, not allowing the fluid to flow through the system? Or does this sound like a water pump? Or what else could it be? Thanks for the help.

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Wednesday, December 16th, 2009 AT 6:45 PM

RASMATAZ

MECHANIC
75,992 POSTS

TY for the donation and Merry Christmas-Have you checked the heater core if tis clogged-up if not do so, if it continues try bleeding the system and see what happens to include checking the heater control valve if it has one

Water pump testing:

One way to test for a bad water pump is to squeeze the upper radiator hose when the engine is hot and idling. Careful, because the hose will be HOT! If you do not feel much coolant circulating through the hose when you rev the engine, the pump may be bad. The other cause might be a bad thermostat that is not opening properly (remove and inspect the thermostat), or a clogged radiator.

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Thursday, December 17th, 2009 AT 10:27 PM

MIKE H R

MECHANIC
3,094 POSTS

The way I am thinking is that if the water pump was bad the car would overheat. With the temp guage going up some after you changed the thermastat is that the system is circulating. With the radiator cap off did you see the coolant circulating? If so there could be a diferent problem. The heater core may be clogged up. You can try draining the system where you can disconnect the heater hoses going to the heater core. Then back flush the heater core using a hose. Flush it until the water runs clear. The only thing else I can think about is the temp controls not working.

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Saturday, December 19th, 2009 AT 11:02 AM