1999 Saturn heater not hot
 

I have 1999 Saturn SL 2 and the when i turn on the heater, the air starts warm and then gets cool. I been reading every where, that thermostat can cause this. The temp gauge stays in middle between C and H and doesn't really move a lot even when the stopped running. Just want get some feed back before taking action..

The average S car temp gauge reading with the car fully warmed up is about a quarter to 1/8 ticks LOL dead center straight up.. you stated yours was between C&h but not where. Is yours in the range I described?

Open the hood before you start the car. Once you start the vehicle, stand near the radiator at the front bumper. Is the fan on rotating as soon as you start up the car?

Is your service engine soon light on? If so, please go to AutoZone or similar and get the codes read for free. Post them as Pxxxx where x is a number.

That's right, the temp gauge isn't straight up when warmed up. There no service engine light on. I will turn car on and see if the fan on when starting the car.

How far is it between the one quarter Mark and the half mark? Most s cars will read within a certain temperature gauge reading if the thermostat is stuck open or partially open. That's what I'm trying to assess.

Also, is your coolant reservoir full when cool?

I will check and take pic of the temp gauge when car warmed up. Yes, the Coolant reservior is full when cool.

https://cimg6.ibsrv.net/gimg/www.sat...6a0063f715.jpg
https://cimg8.ibsrv.net/gimg/www.sat...a54f2dbba6.jpg

The first picture is where the gauge is when driving . The second one the gauge when its sitting idlelling, it goes up little.

Textbook indication of a thermostat stuck open on a Saturn S series. Be somewhere between 11:00 and 12:00.

Do not buy an AC Delco branded thermostat with housing. What you get in the box is a cheap aftermarket brand that is known for its exceptionally short lifetime before sticking closed and overheating your engine.

It would be nice if you can find a stant thermostat to match the original which I believe is 185°. Then you can bring use the thermostat housing already in place.

I recommend you change the o-ring on the housing. You need to be aware of the fact that the OEM housing is no longer available and for whatever reason, the aftermarket gaskets are usually the wrong size if you are reusing the OEM housing. I believe there is also an issue with the newer stant thermostats not fitting into the older OEM housings .

Search over on Saturnfans.com . I remember there was a massive thread there about what fits what and what doesn't fit what.

Make sure you orient the coolant hoses pretty much exactly as they were attached or they have a tendency to leak when they are this old.

Motorad. That's the piece of shayte not to buy that comes in the AC Delco box and of course on its own.

I ordered this thermostat https://www.rockauto.com/en/moreinfo...pt=2200&jsn=14 even tho it's pictured with Motorad thermostat.

Cancel your order or overheat your vehicle at random times while sitting still. When the car is not moving for long enough, the fan under the hood will come on when the temperature gets high enough. It will cool the coolant down far enough to start to close the thermostat. And that's where it gets stuck. Sometimes. Totally unpredictable. Installed and tested in my 97 SC2. Went through five fan cycles, then began to overheat. Cooled ot down, began to overheat again. Cooled it down, opened properly, fan cycled, thermostat stuck, began overheating again. And that was all in my garage. Imagine if I was driving.

You have been made aware. The choice is yours. I don't know what other manufacturers are making these with housings. Stant thermostats are pretty dependable in these vehicles. The hardest part is finding a housing that it's the newer stock and an o-ring seal to go with it. Well it's flat but you know what I mean