99 Trans Am~heater problems

**Leslie Aussem** · 03-18-2014, 05:58 PM

Hi there..i'm new here..and i really like all the threads you guys help each other out with..
I'd like some advice..also..
I have this 99 trans am..and two days ago..no heat...blowing cold air..(replaced the thermostat)..today..
well..get back in start her up..still no heat..
I read here..must bleed the heater // core/ radiator?..
well..ive You Tubed videos..looked for the bleeder valve..i can't find it...i need pictures you guys..
(little history here)..i had colon cancer..used to be spot on..fast learner..the works..and now..brain is fried..you show me something..i get it the first time..i did my own thermostat..took 2 hours...but I did it...
i believe the heater core might be clogged..i watched videos how to do this with a hose..I go out and look..and i dont know which ones they are?...probable on the bottom huh?...
so..I need pics!!! giggle..
anyone help?...i want to bleed the system first..then if that doesn't work..do the heater core...flush..
thanks in advance..much appreciated...look forward to hearing from all of you!..

**pajeff02** · 03-19-2014, 02:27 AM

Welcome to the site!

Could be a couple of things -- a clogged heater core, a stuck open thermostat, or an issue with the blower door in the HVAC system. First, ensure that the engine is coming up to temperature. The upper radiator hose should get hot within a few minutes if the thermostat is doing it's job. Do not rely on the stock temp gauge as it is an "estimator" at best. At the same time you test the upper hose, activate your heating system and set the control for full hot. On the passenger side of the engine, down low above the AC compressor, there are two hoses that run back to the firewall. If water is circulating through the heater core, both hoses should also get hot -- one a little sooner than the other. If one hose gets hot and the other stays cold, then it is likely that the core may be the issue.

I do not know if our cars have a valved heater hose system -- there isn't one on the actual hoses, but it might be inside the heater box. The valve closes off the flow of water through the heater core when you are not calling for heat. On older cars, it was always mounted just before the heater box in line with the supply hose. I am thinking that our cars just separate the hot and cold sides of the HVAC with a door though and that there is no valve. Just thinking out loud...

If you end up with a hot and cold set of heater hoses, after the engine cools off, you can drain the radiator, pull the hoses from the side of the engine, and then back flush the core with a garden hose. If in fact it is plugged, I would strongly recommend flushing the entire cooling system. Let us know what you find.

**2002ssslp** · 03-19-2014, 05:24 AM

^^^^ What Jeff said ^^^^
The heater core is the usual suspect in this case. Warm it up and grab the heater hoses, if both are hot then look under the dash at the hvac controls. Good luck.

**Leslie Aussem** · 03-19-2014, 08:44 AM

Thanks so much..i believe its the core..i will go check for the hoses/touch them..see whats what..*love thinking out loud*...keep doing this for me...the thermostat..is brand new..i felt a touch of heat last nite..i ran it on the freeway..froze my bum off...it was like 20 degrees out..i dont know if it was my hands were so froze that it felt like heat?...or what..anyway..i'm grateful for your reply's..now please dont think i'm stupid..i used to own a bodyshop years ago..80's and i can paint a car, change brakes and the works..but i choose to forget that life...had a husband that taught me all that..yuk!...plus i'm too old now..dont wanna..the radiator..is clear/clean..when i changed the thermostat i put that bucket underneath and caught a gallon of it..so decided to drain it all..it was time and there is now all new antifreeze in there..(hoses were both hot) i remembered that one..(thank you 2002ssslp)...you guys live so close..how bout stoppin by?...lol.

**Leslie Aussem** · 03-19-2014, 08:45 AM

Thanks so much..i think you're right..did the hoses...all good..there..

**KahanaReef** · 03-19-2014, 10:01 AM

Welcome to the site, Leslie! Glad it all worked out.

**Leslie Aussem** · 03-19-2014, 03:04 PM

Well you guys..i'm not up for it..looks like I'd have to take off the front guard/winshield wipers and a ton of computer lines?...whatever..i can't get to the heater core...i see it..i found it..but no reaching it..why do they do this kind of stuff..(i know..so you have to take it in)..well..since you have to take part of the dash out too...i've decided to go to Pontiac dealership i bought it from...and let them fool with it..500 dollars later...omgoodness..what a pip...any other suggestions would be welcome

**pajeff02** · 03-19-2014, 04:10 PM

Did you try backflushing it with a hose? Our Dodge Durango would plug the core about every other year and a few minutes with the hose is all it took to make it throw heat again. Just a heads up -- our engines utilize Dexcool (which is orange in color). No matter what the bottle says about being "universal", never mix the green coolant with Dexcool.

**Leslie Aussem** · 03-19-2014, 07:13 PM

Hi Jeff..i drained the radiator..and put all new Dex in it..(i know about that)..all orange and i bleed it..(meaning i ran it for about 45 minutes without the cap on ..and it finally got all the air out)..tightened the radiator cap..its all good there..the hoses are all pretty new..no leaks ..i even keep it parked on carpet in the garage..dingy garage but all good..now..up top..someone said the hoses to the heater core are on fire wall...i found em..no way can i reach them...without taking the a/c off..or the runner that goes across the windshield..and the wipers..oh gawd...so..i dont know how to fix it..except take in dealership..where I bought it from..if you can tell me..that i'm flushing the system wrong..tell me..by all means...please...

**Leslie Aussem** · 03-19-2014, 07:16 PM

oh..BTW i never short cut on stuff this car ...i used to own a bodyshop in the OLD days..70s/80's with the boyfriend/husband....i can paint cars..rub em out..do brakes and tune ups..just like Marisa Tomei on *my cousin vinny*...giggle..

**KahanaReef** · 03-19-2014, 10:43 PM

Hi Leslie... you should post any tech questions you have in the tech sections. You'll get more responses there

**pajeff02** · 03-20-2014, 02:22 AM

You want to flush the core by pulling the hoses off at the engine -- not at the firewall. If you look close at this picture, at the very bottom, right behind the lower radiator hose, you can see the heater hoses on the side of the water pump. Those are what you want to remove and then using your garden hose flush the core by forcing water first through one hose and then the other, allowing the water to run out of the other hose.

**RONS98TA** · 03-20-2014, 03:43 AM

Originally Posted by pajeff02

You want to flush the core by pulling the hoses off at the engine -- not at the firewall. If you look close at this picture, at the very bottom, right behind the lower radiator hose, you can see the heater hoses on the side of the water pump. Those are what you want to remove and then using your garden hose flush the core by forcing water first through one hose and then the other, allowing the water to run out of the other hose.

A buddy of mine had the same issue of no heat. The issue is 95% of the time a clogged heater core. Under normal circumstances, the water flows in 1 direction causing dirt and stuff to build up inside the heater core causing a clog. If you take the 2 smaller hoses off the water pump housing (look at the pict from jeff) and then take your garden hose and flush it through in both directions. What I mean is blast water through 1 hose, then do the same to the other.

***SMWS6TA*** · 03-20-2014, 08:47 AM

Originally Posted by pajeff02

You want to flush the core by pulling the hoses off at the engine -- not at the firewall. If you look close at this picture, at the very bottom, right behind the lower radiator hose, you can see the heater hoses on the side of the water pump. Those are what you want to remove and then using your garden hose flush the core by forcing water first through one hose and then the other, allowing the water to run out of the other hose.

The 2 hoses Jeff is talking about are almost cut off in the pic. Look at the left wire loom, follow it down to the bottom of the pic. Just as it goes off the pic you'll see the 2 hoses. Pull both off and you'll be able to do as Jeff said. Just be warn you're going to need to add more coolant.

**Leslie Aussem** · 03-20-2014, 09:07 AM

Thank you..i see it..(i get it)..i'm going out to try it..thanks all ....much appreciated..
And yes...i'll post in the tech part next time..(sorry)...