Heating AC and Engine Cooling

THATS WHAT THE OVERFLOW/EXPANSION PACK IS FOR. WHEN ANTIFREEZE/COOLANT BEGIN TO BOIL IT EXPANDS AND IT NEEDS A PLACE TO GO. THERE FOR IT GOES IN TO THE OVERFLOW/EXPANSION PACK. THIS PREVENTS DAMAGE TO THE ENGINE/RADIATOR AND OVERHEATING. THERE IS ALSO THE POSIBILITY OF A MALFUNCTIONING SENDING UNIT/GAUGE.

Either you have the air vents set to "recirculate" which means you are running the same air around the vehicle without drawing any fresh air from the outside, or your heater core is blown.

The thermostat is located on the engine on a 1998 GMC Sierra 1500 standard. The thermostat can be found by following the upper radiator hose directly to the thermostat,

I have the same problem, havn't fixed it yet, but from what I know, all you have to do is replace the thermostat, only like 10 bucks

Check antifreeze level, then thermostat next, heater core last

thru the duct which allows air into the cabin. just like the engine air filter, there is a duct which allows air in and from there it passes thru the filter. a mouse could easily squeeze thru that space

On and '89 I believe it's #17. Iknow your's is a different year. If you have a manual it is in there though. If that doesn't work, (fuse not blown or doesn't correct it), check the connection of the plug at the fan. Still doesn't work, follow the wiring up to the next plug, it will be up near the right of th ebrake fluid resivor. Clean what connectins you can and try that. Still doesn't work, take the plug off the fan motor again and make a pair of jumper wires long enough to reach from there ot the battery. You'll need a couple spade receiver type connectors. put them on the motor and touch the hot & neg wires to the battery and see if the fan starts keep arms, fingers and stuff out of the way of the fan. I had this problem and messed with it & messed with it until I found the corroded connection at the plug near the brake fluid resivor. messed with thte thing for almost 2 hours before I found it. good luck.

Probably low on charge. You can recharge the system but keep in mind you may have a leak somewhere.

Keep in mind that I am only a "shade tree" mechanic, but I do have some experience with this very problem...Take the radiator cap off and look in the filler neck with the engine running. BE CAREFUL!!! If you see bubbles sniff around the filler neck and see if it smells like exhaust gases...like burnt gas. If this is the case, the head gasket or the head itself is the culprit. Exhaust gases will blow passed the gasket/crack in the head and pressurize the cooling system. This pressure probably found a weak spot in the heater core and that would explain the steam. There may be other explanations but this is what happened to me today. When I identified the smell of exhaust gases coming from the radiator,it was evident that the problem was with the gasket/head.

if the fan motor is still good, find a mechanic that knows how to bypass the thermostat and run it to a switch on the dash, thats the cheapest option, and would take far too long to explain on here . Just had the same problem with my 99 camaro and it was an 8$ relay that is in the fuse box under the hood

If the system has a full charge then the thermister is most likely the cause for it not working.

the fan has a thermostat that is set to the manufactures specs. They usually set them pretty low, because of the increase in the use of aluminimun head. If they get to hot they can be warped. hope it helps. duboff I have the same problem - thermostat doesn't open and fans don't come on until temp gauge is at or lose to the L in normal (just before over-heating). What was the solution to this problem?

less heat in your car

first check fuses inside car,look for location in owners manual....if all fuses are good, then you need to find fuse/relay location under hood....next most likely item that affects different systems is a bad electrical ground.....if the fuses dont fix it, go to a mechanic.

its not very common that u have to replace all that because when a car overheats it ruins the engine so u either rebuild it or replace it

check oil for water and radiator for oil, if engine oil has water miced with it ,the oil will be milky looking same does for radiator

there isn't one

relays will be found on inerfenders or firewall

no u can not mix the 2 togather it wil ruin the hvac system

They are designed to come on with A/C, defroster and when water temperature exceeds 235

Check the ignition coil. At cold coils generally operate properly, when the coil heats a failing unit will start to break down and fail causing misfiring and poor engine operation. Second check for a failing ignition controller in the distributor.

Heater core leaking or "bad"/ repair/replace. 4-8 hours labor + parts... pain in the rear (not the cars)

Yes it does and should be checked yearly.

They fog up when water condenses on the surface. If the air inside the car is warmer than the outside temperature you will experience fogging of the inside of the windows. In extreme humidity the problem is worse. You can also see fogging if the heater core is leaking. To dissipate the moisture turn on the defroster.

It could be the ECU engine temp sender, if its different from the guage sender