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Justaguy 02-16-2010 12:54 PM

Car trouble
My 1998 Olds Bravada is producing lukewarm/cool air through its air vents, and the air doesn't get hot. What things should I check in order to determine the problem, and what is the most probable culprit?:(


Ron6519 02-16-2010 03:04 PM

When was the last time the coolant was flushed and replaced? Could be a clog in the hose to the heater box. Is the fan blowing the same as it did before? If the adjustment to the heat is mechanical, it could have come loose. If it's a vacumm adjustment, one of the tubes could be disconnected or clogged. Has anyone worked on the car recently?

brokenknee 02-16-2010 07:40 PM

Make sure you are not low on coolant.

johnnyboy 02-16-2010 08:46 PM

I've had similar issues when there was a clogged heater core.

After you check all the easy stuff,

Locate the coolant lines heading through the firewall to the heat exchanger under the dash. Disconnect both in/out lines from the motor if you can or install T-fittings (you can get them in the prestone flush kit for $3.00)

hook a garden hose upto one, a drainage hose into a bucket on the other. Flush until a big snot shoots out and until the water runs clear. Do the same in the other direction.

Flush the rest of your coolant, refill will fullstrength + DISTILLED water.

Worked for me.

Billy_Bob 02-17-2010 01:42 AM

The temperature gauge for the engine should be about in the middle of the range when the engine is warm. If it is indicating cooler, then replace the engine coolant thermostat.

Also there can be multiple problems. The temperature gauge for the engine can also be reading wrong. The cause of this is usually the "temperature sender". (NOT the engine coolant temperature "sensor" which is for the engine computer!) Then when you fix this, you might then see the temperature is too cool, then realize you also need a thermostat.

And there can be a third problem. The radiator may be clogged and the engine was overheating in the summer, so someone removed the thermostat to get it to cool better! For this new radiator and reinstall thermostat.

The engine thermostat should keep the water circulating hot. Even better is to use a factory service manual along with a thermometer and measure the temperature of the water. Should be what it says in the vehicle factory service manual set.

Anyway once you are sure the water is hot, then also the above about the water being able to circulate through the heater core can be a problem. (As they said above.)

And then there can be a problem with the little "door" in the HVAC system which switches from hot to cold (blend door). If you have an electronic HVAC system, do the following...

Try a "reboot"!

Remove a battery terminal for 10 minutes, then reconnect.

Turn ignition switch to on, but don't start.

Wait 1 minute.

DO NOT touch any buttons in the vehicle during this minute.

Then start vehicle and let idle for 5 minutes.

Drive above 45 mph as soon as possible.

This "reboots" all the computers in the vehicle including the A/C which then "resynchronizes" the actuator doors during the power-up.

This also reboots the engine computer and the idle and driving above 45 mph helps it to "regain" its operating memory.

If this does not work, you would need a GM Factory Service Manual set which would have complete troubleshooting instructions for this problem as well as complete part replacement procedures. Order from or a GM dealer.

You would also need to know how to use a multimeter along with the instructions in the manual. How to use a multimeter...

jaye944 02-18-2010 02:54 AM

not being funny m8
but what have you actually checked/done?

you cant ask a question like that without some kind of info?

have you had a look under the bonnet if so what at?:eek:

cmon help us to help you


Originally Posted by Justaguy (Post 400948)
My 1998 Olds Bravada is producing lukewarm/cool air through its air vents, and the air doesn't get hot. What things should I check in order to determine the problem, and what is the most probable culprit?:(


cowboy dan 04-14-2010 12:17 PM

i have seen alot of that on alot of cars. one i might check is that the blend door on your heating box is working. some are mechanical and some are electronic. ford and gm do that alot

lorel 11-06-2010 04:43 PM

Three things,

Enviromental controls not working properly

Heater core is partially plugged

Antifreeze level is LOW..warning sign is low heat or no heat comming out of vents.

dirtrider73068 11-08-2010 09:14 PM

It could be a stuck open thermostat. I had this happen on my truck took forever to warm up and when it did the temp was really low and not much heat. If you haven't done it anytime soon, thermostat are cheap, change it out you should do it once a year at least. Mine the reason it stuck open was it got hung up on the side and it kept it open.

Scuba_Dave 11-08-2010 10:13 PM

Hopefully almost 9 months later its fixed

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