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That's odd.The coolant flow is basically backwards from earlier chevys but still anything wrong should make it get hotter. I would have to try a winter front,cardboard or similar in front of the radiator and see if the temp comes up,indicating a faulty stat,seems unlikely but ...
1995 huh? Time to check where your heater hoses connect to the engine block. These are known to clog themselves with rust and corrosion preventing coolent to flow through your heater core. Does your heater hoses get hot? If not, your clogged mate!
Make sure the coolant level is full in the reservoir.
If the
coolant level is good feel the hoses that go to the heater core back by
the firewall. If one is cold and one is hot that the heater core is
plugged. I have had fairly good success back flushing the heater cores
and getting them to work. If back flushing does not work than the heater
core will need to be replaced. The entire dash will need to be removed
to do this.
If both the hoses are hot than it may be the blend
door actuator. You should hear a distinct difference in the air flow
from the vents by moving the heat control from full hot to full cold.
The last thing is the t-stat could be stuck open. If this where the case than the temp gauge will also be reading low.
Make sure the coolant level is full in the reservoir.
If the coolant level is good feel the hoses that go to the heater core back by the firewall. If one is cold and one is hot that the heater core is plugged. I have had fairly good success back flushing the heater cores and getting them to work. If back flushing does not work than the heater core will need to be replaced. The entire dash will need to be removed to do this.
If both the hoses are hot than it may be the blend door actuator. You should hear a distinct difference in the air flow from the vents by moving the heat control from full hot to full cold.
The last thing is the t-stat could be stuck open. If this where the case than the temp gauge will also be reading low.
Both of the hoses at the heater core should be hot. If one is cold the heater core is plugged.
You can think of it this way. If the thermostat was stuck closed and you checked the upper and lower radiator hoses with the engine hot the upper hose would be hot and the lower hose would be cool because there is no flow. If you check the hoses with a properly working t-stat both hoses will be hot when the t-stat is open and coolant is flowing.
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1st of all, you need to check your anti-freeze level. If its not full, the coolant cannot/will not flow throughout your heater core which the coolant flow through to heat your vehicle. If it is indeed up to the proper level? Than, yes I would look into the thremostat. It may not be opening up.
LOOKING AT HEATER CORE TOP HOSE COOLANT FLOW IN BACK OUT THROUGH THE BOTTOM HEATER CORE HOSE CHECK WATER PUMP BYPASS HOSE SEE IF IT GETS HOT.IF NOT COULD BE BLOCKAGE AT BYPASS HOSE FROM WATER PUMP OR WATER COULD BE FAULTY GETTING TOO WEAK PUMP COOLANT THROUGH SYSTEM.IF COOLANT GETTING HOT GOING TO HEATER CORE THE HEATER CORE AND COOLANT SYSTEM NEED FLUSHING OUT.
Find where both hoses are going to the heater core from the firewall side after engine is up to temp.Touch them with your hand.If they are both quite warm the water is flowing thru the heater core. If only one is hot the core is stopped up. If both are hot and still no heat the heater door in the heater box is staying closed.
Unless you have symptoms of over-heating, I rather doubt that your water pump is a problem. I recall that my water pump had a metal impeller (1992 C900); I haven't heard of a plastic impeller on a Saab pump before. (Most pump failures are the bearing seal, and the pump leaks coolant) If your temp gauge is slightly low (and was OK before) I'd rule out water pump issues.
You might have one or more of the following issues:
did you use a Saab thermostat? The Saab stat has three stages (no flow to rad - cold; flow to rad and heater core - normal operation; and no flow to heater core, full flow to rad - overheating) that most after market stats don't.
did you use a low temp stat? this opens at about 82 deg (rather than 89 deg), and will run cooler during the winter, hence you gauge will show lower than the mid point. The big benefit is that your engine won't overheat during the summer (a very good thing!) with the low temp stat.
has your rad and heater core been flushed recently? If the heater core is obstructed flow will be reduced and the heater will run cool. Feel the rad and heater hoses when your engine is warm; if heater hose is much cooler than rad hose with heater temp set to max, then core flow is likely restricted, or valve is not moving much from the shut position.
is you vacuum tank properly connected and are there no leaks in the vacuum piping? The tank is in the driver side rear wheel well below the trunk deck on a convertible, and in the passenger side front fender area on the other cars. It's a white bottle with one or two hoses connected to it. If not properly on, your vacuum operated heater flaps won't move. Does the air distribution knob make sucking or hissing noises when you set it to different positions? If not, check the tank connections, look for vacuum line leaks, then suspect the vacuum valve behind the distribution knob.
Lastly, the shaft connecting the temp control knob to the valve behind it may not be properly in place. This can be inspected, and adjusted if necessary, from the speaker/vent cutout on top of the dash. Make sure you re-connect the black flex hose to the air vent tube, or you'll get no defrosting afterwards!
remember, the centre vents always blow cold air; a brilliant idea from Saab so the driver (and passenger) can get fresh air in the face and stay awake while the rest of the driver, passenger and car is toasty!
see http://townsendimports.com/Web/cooling_system_folder/thermostatreplacement.htm for flushing and stat replacement info
I have the same model suburban. I replaced the heater core. You will probably end up replacing both. You can buy them at Oreilly or AutoZone. and install yourself with a manual.
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