Unwanted hot air into cab

[Fu Manchu]

Vacuum to the tap is not the problem, because I wired the tap closed and still had the problem. A new development is that I removed the tap altogether and replaced it with a solid plug, stopping any water flow. This temporarily solved the problem and my airflow into the cab returned to normal outside air temperature, like it used to be. When I blow through the removed tap with my mouth, some air does leak through, even though this is a new tap. Thinking that I had bought a dodgey tap (through the internet), I ordered one through my local Holden dealer. When I went to pick it up, I tried the blow-through test, and that one behaved the same - you could blow air through while holding the lever closed. The attendant then took it out the back and tried it with water. He said yes, some water does leak through when closed. How hard can it be to make a simple tap that closes off properly? Any plumbing store would have one. Anyway, I told them there was no point buying another tap just like the one I had so I'm back to square 1. I think I've eliminated everything except perhaps that a dribble of water is supposed to pass through, and my problem is that the air mix flap on my car is not sealing off properly. However, one of the 3 service centres that I have paid to look at this said that they checked on that. I will have to do it myself. But i can't find out how to get at it. Can anyone advise how I expose the warm/cold air flap, that I believe is down by the left foot rest? I can't see it or how to get at it. Will try flushing heater core - but I can't see how that would be a cause of too much heat, only the other way. Thanks.

It would be logical that a small amount of flow is allowed through, to avoid coolant just sitting. It wouldn't be enough to make the difference you are experiencing.

Be worth checking the knob for the temperature.
Remove the assembly from above the headunit, give it visual check over and focus on the part at the back that controls the temp. It's a lever thing.

The arm for the internal flap that restricts hot air might be dickie.

There could easily be some foam stuck in the flap allowing air to circulate through the heater core compartment (which won't cool immediately) Adhesive foam is used around the edges of the flaps... no wait I'll use the word doors, around the edges of the doors in the HVAC. They drop away and get brittle/crumble etc. I found heaps in the VE HVAC when I pulled that apart.

Have you got climate control or a manual HVAC control?

 

[Fu Manchu]

The design of the HVAC, still allows hot water through the heater core, it controls the temp by isolating the heater core in a compartment. cold = closed at one end, warm = flap/door ½ open, full hot = door closed fully at opposite to cold.

 

[ChrisG777]

Wouldnt it be as simple as swaping the hoses around and see what happens

U can try turning the A/C on.

The A/C struggles against the 8 degree air flow temperature difference, so is just comfortable with an outside air temp of about 25 degrees, but can't compete when the day is much warmer than that.

 

[Fu Manchu]

So heater tap checks out.

Are the hoses fitted to the correct pipes in the firewall?
I know in the VE, Holden directly point out to not get this muddled.

Heater controls? Remove and check over for correct operation.
Actuator or actuator mechanism operating correctly?
Blocked or obstructed internal HVAC door.

 

[ChrisG777]

It would be logical that a small amount of flow is allowed through, to avoid coolant just sitting. It wouldn't be enough to make the difference you are experiencing.

Be worth checking the knob for the temperature.
Remove the assembly from above the headunit, give it visual check over and focus on the part at the back that controls the temp. It's a lever thing.

The arm for the internal flap that restricts hot air might be dickie.

There could easily be some foam stuck in the flap allowing air to circulate through the heater core compartment (which won't cool immediately) Adhesive foam is used around the edges of the flaps... no wait I'll use the word doors, around the edges of the doors in the HVAC. They drop away and get brittle/crumble etc. I found heaps in the VE HVAC when I pulled that apart.

Have you got climate control or a manual HVAC control?

 

[ChrisG777]

It would be logical that a small amount of flow is allowed through, to avoid coolant just sitting. It wouldn't be enough to make the difference you are experiencing.

Be worth checking the knob for the temperature.
Remove the assembly from above the headunit, give it visual check over and focus on the part at the back that controls the temp. It's a lever thing.

The arm for the internal flap that restricts hot air might be dickie.

There could easily be some foam stuck in the flap allowing air to circulate through the heater core compartment (which won't cool immediately) Adhesive foam is used around the edges of the flaps... no wait I'll use the word doors, around the edges of the doors in the HVAC. They drop away and get brittle/crumble etc. I found heaps in the VE HVAC when I pulled that apart.

Have you got climate control or a manual HVAC control?

I have already taken the dash centre panel off and checked the knob, which is working correctly. Maybe it is the hot/cold door in the HVAC, even though one service centre said they had checked that. So in my earlier post I said I was planning to check it myself, but I can't find how to get to it. I asked if anyone could advise where it is and how to expose it. i think it is near the left foot rest. It is a manual system.

 

[ChrisG777]

So heater tap checks out.

Are the hoses fitted to the correct pipes in the firewall?
I know in the VE, Holden directly point out to not get this muddled.

Heater controls? Remove and check over for correct operation.
Actuator or actuator mechanism operating correctly?
Blocked or obstructed internal HVAC door.

It looks to me like the connectors of the pipes to the firewall are tricky to remove, but i'll try again. I've had the centre dash off and the (manual) heater controls are working correctly. The heater tap is going open to closed correctly. It only leaves the HVAC air flow door, but I can't get to it. Any advice on how to expose it?

 

[Fu Manchu]

There is a fair bit of this that can be super hard to get to with the instrument pad still on the car and I can bet no one wants to remove that to sort things.

I'll get a photo of the hoses in the engine bay. Easy to have them muddled if they have been replaced. Maybe that happened before you owned the car?

 

[Fu Manchu]

It only leaves the HVAC air flow door, but I can't get to it. Any advice on how to expose it?

You have to degas the AC.
Remove the centre console
Remove the instrument pad/dash.
Lower the steering column
Remove the HVAC box that the car was built around.
Pull apart the HVAC box.

Negatives:
Huge f'n job!

Positives:
Good chance to fully clean and de-fungus/mildew the internals.
Redo seals. (I went to Clark Blubber for most)
Replace the heater core (otherwise you'll be doing this again)
Replace the AC Evaporator core and Thermal Expansion Valve. (also doing this again in the future if you don't do it while you have the chance)

 

[ChrisG777]

There is a fair bit of this that can be super hard to get to with the instrument pad still on the car and I can bet no one wants to remove that to sort things.

I'll get a photo of the hoses in the engine bay. Easy to have them muddled if they have been replaced. Maybe that happened before you owned the car?

Thanks. But I have had the car from new and only had professional services.