View Full Version : No HEAT!!! Help!!! 1996 FWB

10-20-08, 10:42 PM
This is crazy! I froze on my commute to work this morning! I have a 1996 FWB. What happens is that the heat is not coming out of the vents and there is no air coming from the floor vents anymore. I set the climate control to 90 degrees and nothing comes out of the floor and not much air is coming out of the defrost vents but you can hear the fan running full blast. If I press the defrost button it will open up and blast the windshield but it is only luke warm. I tried changing the thermostat and it did nothing. both heater core hoses are HOT after running the car so the coolant is circulating. It was like this the entire way to work and I have a 30 min commute. I kept trying to switch the climate control off and on and I even tried the econ mode to no avail. I don't know if this is related but the heated seats are acting funny too. You will turn them on and they will decide when they want to work.

What is even more odd is this. I have a 1991 Cadillac Deville doing the SAME thing with the heater. I drove it the other night about 45 minutes each way on a trip, heat set to 90 degrees and it only blows lukewarm air out of the defrost vent and a little out of the floor. I also tried switching the temperatures on both vehicles. Am I doing something wrong? Everyone was able to help me the last time on here. You all have good information to offer so I'd appreciate anything on this!

Thank you!

10-21-08, 01:53 PM
Time to flush heater core...

10-21-08, 02:09 PM
Time to flush heater core...

I agree, Ive fixed about 5 94-96;s same thing also back flush the lines that go to the water pump., often the restricter gets blocked, remember reverse flush it,

10-21-08, 05:52 PM
Will this fix the problem with the air not coming out of the floor vents?

10-21-08, 07:38 PM
sounds like you have at least 2 issues, the next thing I would do, is remove the plastic cover that go's under the dash, on the passenger side, just above the trans hump you will see an actuator, with a vac line going to it, it should move freely when you change from def to heat, if not, manipulate it by hand and see if that has an effect, Im guessing it will,

10-21-08, 09:54 PM
Should it move freely or how can I tell if it's bad? Thanks!

10-21-08, 10:29 PM
Should it move freely or how can I tell if it's bad? Thanks!

it should move when you change, from def to heat, or if you go to a/c it should move to the venting position, you can gently push or pull it to put it through it paces, , im guessing its not completely closing, for some reason,
could be something in the way ,
over on the passenger side just above the kick panel there is another vac device for the mixing door, this mixes outside air with the heated air, if you play around with them, and the heater core isnt blocked , you should be able to get all the heat you want,
I have any of the parts you might need is you find one thats not working, i/e vac devices, where are you located??

10-22-08, 09:41 PM
I removed the underdash cover to take a look at mine because I'm having the same problem. The only thing that I seen move was a "door" above the trans hump. This door opened when I hit AUTO and closed when I hit OFF. Nothing happened when I hit DEFOG. Also there was a spring that was out of place. The spring was positioned on the pivot of this same "door". And still not heat. What exactly should I pay attention too?

10-22-08, 10:17 PM
the door over the trans hump directs the air to vents for a/c, floor for heat windshield for defog, over on the pass side above the kick panel area, theres another door, this is the mixing door, it blends the outside "cold" air with the hot air off the h/core, if the cores circulating and the engines at temp, the only other thing is the mixing door, you can GENTLY push or pull on the activator arms to close the doors, or redirect the venting,I can furnish pics tomorrow if you cant figure it out,

10-22-08, 10:52 PM
That would be great for the pics! I'm in PA by the way. I will let you know what I find when I tinker around under there. I have a Buick Roadmaster unit I may install at this time as well. You don't think the climate control unit may be bad? I had a digital one go bad in a 1992 Oldsmobile Cutlass convertible of mine. I bought a refurbished one from a stealership and never had a problem after that. This is why I may just hope the Roadmaster one works...

10-23-08, 08:17 AM
just got into work after a 40 mile drive with minimal heating. I removed all of the underdash hoardings and paid close attention. my observations were:

No air flow to winsheild when I hit DEFOG or DEFROST. I drove my entire journey with a haze on the inside of the windsheild.

just above the trans hump area, I can feel warm air but it is not moving, but immeadiately to the right of the hump is cold (dramatic change)

can hear the fan work and feel massive amount of cold air on the passenger side

in AUTO mode I moved the the temp through the range and could hear the fan speed increase. at 70 -72 slow speed, at 72 -74 more speed, at 75 and above AUTO high speed at 85 the display changed to HI FAN.

Hope the description is clear and yall can offer some help.

10-23-08, 07:48 PM
ok, we are assuming you have tested and or flushed your h/core, both hoses hot to touch
#1 is the vac control for the windshield defog
#2 is the vac device for floor/vents
#3 is the vac control for the fresh air mixing door,
#4 is the electronic control for temp, thats what the digi gauge on the dash controls, if necessary, apply vac via a vac pump, or ??, to each device and see if it travels through its range, the electronic control has a hole in the middle, with an aluminum slotted hole in it, put your finger on it and move the dash button all the wasy up and then down 90-60, you should feel that aluminum piece move, if it were me, id do some disconecting of the actuater arms and move things around until I got heat, maybe some rubber bands to hold things in a heat position, at least until you have time to dig deeper, driving with a fogged up w/shield is dangerous, and driving with no heat is friggin painful, I will add most of the heat issues Ive solved on these models have been h/core related,

10-23-08, 11:17 PM
Thank you so much Hemi. The visuals represent a top grade example of how useful this forum can be! I have my whole dash torn apart underneath however I am going to flush the heater core too because I think it may be restricted. Thanks!!

10-24-08, 01:04 PM
thanks for the pics.

10-24-08, 08:40 PM
:thumbsup:no problem guys, hope it helps

10-24-08, 11:22 PM
is there an in car air filter?
What is the radiator looking thing next to the heater core and should water drip off of it?

How did you get it off, I removed all the bolts I could see but it won't give. maybe I am missing a couple?...any hidden screws/bolts?

10-26-08, 01:10 AM
No in car air filter on the FWB's.... My 00 PAU has one, still need to find it, not easy to get to from what I gather...

10-28-08, 08:34 PM
hey 69hemi, i have the same problem. i have backflushed the heater core and lines to the water pump. also my vents work when changing from heat to defrost and air mixer door moves when going from cold to hot on temp range. the one thing i have noticed is that while on auto and the temp on 90 the a/c will cycle. can you help?

10-28-08, 09:55 PM
theres a button on the dash control that says econ, that is for winter time, and stops the a/c compressor from cycling, also saves some small amount of fuel, if you have done all you say, and both heater hoses are hot to the touch, then I would look at the temp control, #4 in the pic, also verify the cold air mix door isnt opened up too much far left (pass side)

10-29-08, 05:25 PM
When the car is up to full operating temperature. Feel for different temps between the heater core supply and return hose. If they are both hot, the core flush won't do much. If one is noticeably different from the other, that's the problem.

10-29-08, 08:37 PM
everything seems to be working under the dash. i went back to the engine compartment and noticed the hoses coming from the water pump one is hot the other is cold. i have took them loose and flushed them and water comes thru with ease. but it seems there is a plastic T in the top hose that comes from the waterpump to the heater core it T's and goes to the overflow tank. the hose is hot from pump to the T but cold after. but like i said before i have taken hoses lose and run water thru both directions. sounds like i have the problem you are talking about DELZY. what is the corrective action?

10-29-08, 10:20 PM
if im reading your info right, it sounds like your core is blocked, did you reverse flush it?, pushing water through in the same direction wont dislodge anything, the more pressure the better , theres a lot of ways to clean the h/core, , In my case I removed the restrictor in the h/core line, allowing a more robust circulation, the factory manual says its there to prevent over pressure to the h/core and possible leak, but ive been running without the restrictor for 3 years no issues and tons of heat!

10-29-08, 11:39 PM
Keep the restrictor in, it is needed, it is a bypass for the heater core, no restrictor, more water bypasses (not as hot), blocked restrictor, 100% water through core, can cause noise and premature core wear, but it will force more water though core.

10-30-08, 10:47 AM
i guess i was flushing the wrong direction. i'm sure this is my problem. thanks alot you guys

10-30-08, 06:48 PM
problem solved. the waterpump return was clogged. i now have heat!!
like i said before thanks alot guys. this forum has been very helpfull.

11-01-08, 07:16 PM
Cool! We try!!

11-01-08, 08:52 PM
I wish I was that lucky. This is week 2 for me and no progess. I am not getting no heat, no flow through floor vents and nothing happens in DEFOG or DEFROST. Can hear the fan but no flow. IN/OUT hoses at heater core both hot, new tstat. please help.

11-01-08, 10:28 PM
Are you getting airflow Firstime? Anywhere?

11-01-08, 11:27 PM
no none that I can tell.
when I cycle through from 90 to 60F I can see air inlet door open.
I can see the temp valve rotate, so I assume it work.
the blower works but no flow through any of the vents..
heater core hot, evaporator cool,
control unit???

11-01-08, 11:47 PM
No air anywhere? default is usually defroster (safety) and some air bottom. Wonder if an air door is stuck closed. My old 85 Cutlass was notorious for that, it was sloppy install from the B&A guys doing the "bigger the blob the better the job" installs.....

Is eWill3rd or AJXTCMan here? He works a Cadillac dealer and might be able to get the factory docs and post, they show how to read the display for what is going on.

11-02-08, 07:55 AM
no flow anywhere!

11-02-08, 09:19 AM
with ignition in run I selected Auto then hit DEFROST...hear the fan go at high speed. Then when I hit DEFOG the fan speed slows down and that is all I get. Don't see any of the arms move, neither do I hear the doors open/close.

11-02-08, 11:45 AM
with ignition in run I selected Auto then hit DEFROST...hear the fan go at high speed. Then when I hit DEFOG the fan speed slows down and that is all I get. Don't see any of the arms move, neither do I hear the doors open/close.
listen for a hissing sound around the pass side , sounds like maybe a vacuum line is off
also try pushing or pulling (gently) on the arms, at least you can see whats not working, the other method is apply vacuum to the activator with a vac pump or even a piece of vacuum hose and suck on it, that will allow the doors to travel and should tell you were you need to go, then tell us what you find

11-02-08, 09:34 PM
I've made some progress. Went to junk yard and got the vacumm control device above the trans hump(MODE), from a 93 roadmaster, and made the switch. This corrected the problem, I am getting some heating and flow through the different vents. But still it seems the heat is not very hot.
Will see how it does tomorrow on the way to work.

And, a few of the H-AC control buttons are not lit. (out temp, fan^/fan v, econ, off,

Thx for the help.