Heat and A/C not working

Discuss any problems, warranty, repair, or replacement issues you are having with your Vibe & Matrix
Post Reply
mcharper1
Posts: 5
Joined: Sun Sep 20, 2020 10:15 am

Heat and A/C not working

Post by mcharper1 »

I have a 2003 Pontiac Vibe. We just bought it and the A/C is not working, and neither is the heat. The blower motor works, air is blowing out of the dash vents, but it like it is vented air from outside. It is not hot or cold. The previous owner told me they were both working and the air quit. They didn’t even know the heat wasn’t working, it is summertime, so I understand that. Any ideas what would cause them both to go out at the same time? Where can I even start?
User avatar
joatmon
Posts: 10018
Joined: Fri Mar 21, 2003 5:19 am
Location: SMC MD

Re: Heat and A/C not working

Post by joatmon »

Welcome to genvibe.

There's things that cause the heat to not work, and there's things that cause the AC to not work, but identifying one common cause for both is a challenge.

The only thing I can think of would be the blend door control. The temperature control in the dash moves a mechanical cable that moves a flapper in the air distribution system. In these cars, there is heated engine coolant always running through a heater core in the center of the dash, and the door controls how much air gets passed through that heater core. When you set it to hot, all the air goes through it, when you set it to cold, none is supposed to go through it.

There was a common problem in the first years where that cable was not aligned properly, causing some air to pass through the heater core even when set to max cold, causing the AC to not run as cold as it could. A thread on that is at viewtopic.php?t=1004 unfortunately the pics form that thread have disappeared.

Seems a long shot, but perhaps that control cable has come off somewhere, and the door is partially open. I'd think that you'd still get some heat coming out if that were the case though.

Now maybe the AC quit and the blend door is stuck in the cold position.

If its' independent issues, then
A likely cause for no heat is an air pocket in the heater core, this can happen if the coolant is changed and then the system isn't properly burped.

AC failing in Vibes tends to be either a leak and the refrigerant level is low, or the AC compressor clutch has failed.
Image
mcharper1
Posts: 5
Joined: Sun Sep 20, 2020 10:15 am

Re: Heat and A/C not working

Post by mcharper1 »

Thank you, I will check all of this and see what I come up with.
mcharper1
Posts: 5
Joined: Sun Sep 20, 2020 10:15 am

Re: Heat and A/C not working

Post by mcharper1 »

So today I put in a new thermostat. That didn’t fix the heat. I checked the cable to the blendor and it was off, so I reattached it and made sure it was working. Still no heat. I took the hoses off going to my heater core and used a water hose to flush the heater core, it is flowing great, no obstruction. I turned the car on with the two heater hose lines unhooked and nothing is coming out of either of them. I used the water hose to pressurize one of the lines, and it pushed water and antifreeze out of the other line. No stopped up lines.

What would cause no water to be pumping through the line to the heater core? It’s not the water pump because the vehicle doesn’t over heat and runs just fine.
User avatar
joatmon
Posts: 10018
Joined: Fri Mar 21, 2003 5:19 am
Location: SMC MD

Re: Heat and A/C not working

Post by joatmon »

That is freaky.

If you use the water hose to push water into one of the places the disconnected heater hose would connect to, does anything come out the other one? (if you push water into the engine block, does it come out the other hole?) When everything is connected and the car gets up to temp, do the heater hoses get hot?

I can't remember if it was on my Vibe or another vehicle, but one time I had air in the heater core. Coolant still flowed through it, but it went straight from inlet to outlet running through the least possible amount of core instead of all of the core passages. I swapped the heater hoses, hooking up the supply hose to the core outlet, and the take up hose to the core inlet, and that was able to fill up the core and push the air bubble out. Might be worth a try.

The only thing I can find showing the coolant flow is the attached PDF. Looks like water should be pushed through the heater core even if the thermostat is closed.
Attachments
1zzfecoo.pdf
1ZZ cooling system
(18.95 KiB) Downloaded 81 times
Image
andrewclaus
Posts: 482
Joined: Tue Oct 03, 2017 6:38 pm
Location: Golden, CO

Re: Heat and A/C not working

Post by andrewclaus »

All I can add is that you should be able to feel a difference in temperature (delta T) between the inlet and outlet hoses on a functioning heat exchanger (heater core or radiator). An infrared temperature gun (I got mine for less than $20 on eBay) is valuable for troubleshooting any heating problem.

And just because the blend door cable is attached, does that mean the door is working? If there's no delta T on the hoses, I'd suspect there's no airflow over the core.

I concur with the possibility of air blockage in the heater core. I also wonder if the water pump is damaged, has enough flow for engine cooling, but not the heater core, which has more resistance with smaller hoses.
mcharper1
Posts: 5
Joined: Sun Sep 20, 2020 10:15 am

Re: Heat and A/C not working

Post by mcharper1 »

Thank you for the responses. It was air. I searched for information on this problem and came across another post where a guy said he was experiencing similar issues and revved the engine to 2500 RPM’s and kept it there until the air circulated out. I did that, and it worked, problem solved.
User avatar
joatmon
Posts: 10018
Joined: Fri Mar 21, 2003 5:19 am
Location: SMC MD

Re: Heat and A/C not working

Post by joatmon »

Sweet.

So now on to the AC?
Image
mcharper1
Posts: 5
Joined: Sun Sep 20, 2020 10:15 am

Re: Heat and A/C not working

Post by mcharper1 »

The A/C is working now. I replaced the dryer, orifice tube, and compressor replaced. The biggest issue with it is that I have had it in two different shops, and it still will not blow really cold. I mean, it blows cold, but not what I expect it should. It also doesn’t blow very hard. Even on high, I would expect it to blow harder than it does.
Post Reply