Hello,

I and my mechanic are at a complete loss, and the local dealership I also sent my car couldn't figure out this problem!
I have a 2009 Equinox. I have owned it now for just over a year - up until Oct 2017 I had no hvac issues:

I brought my car to the shop when I suddenly lost heat. - The heater core WAS plugged but here is where it gets really bizarre

What is happening basically is this: The system is flushed, the heat comes on not hot - and runs maybe 2hrs then cuts out completely. This is intermittent. The dealership had heat for about 3hrs then system went stone cold again.

Without a lengthy explanation the following have been replaced:
Heater core (was clogged initially)
Blend door / actuator (known to fail, replaced since dash was apart)
thermostat (I replace anyway once a yr)
Head gasket (had blown with no symptoms, shaved off some of head, minor warping - sent to machine shop shaved, etc and resealed)
Radiator (was partially blocked)
Water pump (not sure if this was faulty - but we did anyway)
System has been flushed at least 15x - there is no air in system
Found blockage in 1 hose off waterpump (a ball bearing??)
All hoses removed/inspected no further blockage..

AND...STILL NO HEAT!!!!!

Is there an electrical cause we are missing?
ECM?
Relay?
The blower motor does run, blows good - just cold.
The engine does not overheat..

Anybody have an idea's I would greatly appreciate it. My car has been in the shop since Oct with this issue.

 

In what order was the work performed? If the heater core was one of the first things they replaced and then they proceeded to flush the cooling system numerous times thereafter, it seems plausible that the new heater core could have a blockage in it again considering all the blockages (including a ball bearing of all things) that were found elsewhere in the cooling system.

The one part I don't see on your list is the coolant lid on the reservoir. Replace it ASAP.

Also, do you know what part was installed when you replaced the water pump? If you have the 3400 V6 engine, the impeller on the new part MUST look like the one pictured below.



The water pump for the 3.4L engine in the Equinox/Torrent is different than those used in the older 3.1L/3.4L V6 engines that GM used in many applications. The water pump for those older 3.1/3.4L engines used a stamped steel impeller with only 6 fins. They will fit perfectly into the Equinox/Torrent 3.4L, but they don't provide enough coolant flow. Most water pump manufacturers have acknowledged this, but some have not and their catalogs incorrectly state that the pump made for the older engines (with the stamped steel impeller) is compatible with in the 3.4L engine in the Equinox/Torrent.

You can also try re-calibrating the HVAC actuators. To do this:

1. Make sure ignition key is in the OFF position.
2. Remove the 10A HVAC/RFA fuse (located in instrument panel fuse block) for a minimum of 10 seconds.
3. Install the HVAC/RFA fuse.
4. Start the vehicle.
5. Wait 40 seconds for the HVAC control module to self-calibrate.

 

Hi There,

Thanks for the advice - I will forward to mechanic.
The work in order went:
Heater Core / Thermostat/ Coolant Temp Sensor (Thermostat & sensor I opted to have done as part of "tune up" to system)
Had heat for about 2hrs, then it went out...returned to shop the following monday

Heater core seemed blocked again - so replaced a 2nd time, and blend door and actuator since they are known to fail in Equinox
The coolant flowing into core seems hot going in, and cold coming out intermittantly.
Decided to flush system to make sure no air in system.
During the flush milky white liquid was found, as well as gritty debris and rust (like somebody used that jb weld crap)
system was flushed multiple times to clear out the debris, weld particles etc
ended up the head gasket was leaking
did head gasket, was slightly warped and sent to machine shop for tooling, shaved, returned and reinstalled.
Also did water pump at this point.
flush system, and heat did not work.
Check of radiator found it was partially blocked, so a new radiator was installed - good pressure in and out of radiator.
still no heat
ambient air temp sensor was changed
no effect on heat
pressure into heater core is good, hot, but out pressure is weak, warm
sent it to local chevy dealership - after two trips there they found a hose off of water pump was blocked with a cap (like a liquid cement cap) and ball bearing.
suggested a previous owner may have sabotaged the system but putting debris into system, plausible, but system ran fine last winter and all through the summer.
suggested mechanic remove and inspect all hoses for further blockage
testing of system - the heat remained for about 2hrs then blowing cold again.
last week all hoses were removed and inspected, no further blockage seems to be evident. -
This week mechanic is changing heater core again (it was under warranty).
We are also inspecting the hvac control unit for any shortage etc, though the blower motor runs fine, and can hear the actuator move the blend door.

 

Have same issue any fix yet? Been racking my brain for a week now seem heater core restriction lower is hot upper is cold but flushed multiple times

 

4 cyl. or 6 cyl.? Flushed AF in my 2008 6 cyl. and had no heat. Took shroud off top of engine and found bleeder valves(2 or 3) and bled them. Instant heat! Careful as not to tighten them too tight as they are made of brass and break easily. Good luck!

 

hi, my friend had kinda same problem. the return hose from the heater core has another hose coming off of it going to the over flow. He put a reducer in that hose close to the over flow tank. Now he gets more flow through the heater core directly from the engine, lots.of heat. Now his is a little newer but maybe track that hose and see if you have one going to the over flow.