98 Saturn SL1 - Heat blows cold at Highway Speeds, A/C works great, HELP!


Asked by Nov 26, 2015 at 03:30 PM about the 1998 Saturn S-Series 4 Dr SL1 Sedan

Question type: Maintenance & Repair

I have a 1998 Saturn SL1 with the 1.9L 4cyl. She is a complete base model
(5spd Manual, crank windows, no power steering, etc). I owned a 94 SL1
about 10 years ago that was totaled in an accident that I absolutely loved
(she had 212k  miles on her and didn't burn, or leak a drop of oil).

The 98 I bought about 3 months ago, it was a 1 owner with just 99,305 miles
on it. I picked it up for $900. The 2nd day I had it, the "low coolant" light
came on and I immediately took her to the shop. They explained that that
radiator had a split down the side and she was leaking coolant very bad. I
had them replace the radiator, the thermostat, and the coolant overflow cap
(as I had heard the cap often fails on these engines). So for most of the
summer I used the car as a commuted to work because of the
ASTOUNDING gas mileage you get out of these cars. The A/C works very
well and I never saw any more engine heat up, nor had any other problems
with the car.

I have a much nicer vehicle that I prefer to garage in the sometimes brutal
winters here in Idaho (a 2012 E350) to avoid getting the de-icer used on the
roads on the paint, gravel pits from the sand, and from risk of collision
(either by myself or another driver), but I digress.

The problem with the Saturn is, that she has no heat. If I start the car and let
it idle for a half hour, I will get in and the heat gauge shows she's running
perfectly, just between the quarter mark and the half mark on the heat
gauge. She does have a little heat however, if I put the blower on full, within
30 seconds the air goes cold. During my commute, the car blows cold the
whole way (Roughly 20 miles). Since the radiator, thermostat, and coolant
overflow cap have been replaced, what could be causing this?

There is no leakage of oil or antifreeze on neither my garage floor at home,
or my parking space in the garage at work. I checked all fluid levels when
the car was cold, and they are all at appropriate levels. I also inspected the
heater controls themselves and the mechanism that changes the airflow (the
little slider that goes from blue to red, or cold to hot) and it works perfectly,
opening the correct "door" to the cabin. Could this be due to a blown head
gasket? Note: I do notice after driving for some time, at idle, that if the
heater is off and the car is running, the heat gauge goes up to the 1/2 mark
and the cooling fans kick on bringing the temp gauge back down to a
normal level. After spending just about $1200 total on this car (the purchase
price and the radiator, hose, thermostat, and overflow cap, replacements), I
am hesitant to repair it for another $500-$1000 for the gasket. Any help
would be greatly appreciated!

8 Answers


First let vehicle reach operating temp and feel the heater hoses going into and out from heater core if the both feel hot and the same temperature blend door cable may have come off.

1 people found this helpful.

It could be that they installed the thermostat backwards you know when it was replaced I don't know I would go back to the repair shop and let them deal with it cuz in a way they might have created the problem?

1 people found this helpful.
Best Answer Mark helpful

Thank you both @firebird338 and @akasnacker after pulling it apart to do some preventative (and albeit needed repairs for a 18 year old car) I noticed in fact that they did install the thermostat incorrectly. I have it reversed and resumed normal operation).

1 people found this helpful.

Im glad we both could help you. Now go forth and pay it forward! Happy motoring!

1 people found this helpful.

hmm.. the thermostat is in the water outlet.. I just changed mine. I don't see how it could be installed backwards.

I have a 1996 SC1 with just over 300,000 miles that is doing the same exact thing. I checked and all hoses are warm Also the water temp and the water level warning lights have started blinking. I was told that the water resivor may need to be taken out and thoroughly cleaned as there is a sensor or sensor inside that cause malfunctions when the become dirty and corroded. It was also recommended that I drain and flush the entire cooling system which sound logical. I am going to do both and would also like to check this blend box thing as well. Can someone tell me where this is located. All I know is there are no obvious causes and would appreciate any feedback. Thank you.


Blend box thing?


Did you mean Thermostat?

Your Answer:


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