Ongoing Air Conditioner Problems

[Black_Bug]

Hey everyone,

I'm going to have to apologize in advance for the long post.

I am having an ongoing problem with our family car's air conditioning and I've got to the point where I'm pretty well stuck. I really don't want to fork out more money for an a/c specialist so if anyone has had similar problems please let me know what you did to fix.

The Car: 02 VY SV8 (Auto)

The issues were,
1) A/c Compressor engaging but blowing hot air
2) Vent's not switching great between settings (feet, window, etc)
3) Cuts out all together when turned up to 3rd setting (then intermitted for 2 seconds when starts up again)
4) Weaker air flow than my parents car (VY V6)

What I've done
So, I took the car to an auto electrician/air con specialist who checked the a/c system over, pressure tested, etc and was found that the compressor was leaking so $1300 later I had a new compressor fitted. The air is slightly cooler but no where near what I think any air con should be. I can have it on Hi, flat out cold on a 25-30 degree day and I would never feel comfortable in it, the car never gets cold. (It also has very dark tint so there isn't much sun getting in - possibly not legal tint). They checked over the whole system, I had already checked the evaporator core (searching DIY's on this forum) which is like new. The whole system was re-gassed with new compressor, but no joy.

Going on what some people have said on this forum it could be the actuator(s) that open/close the flaps for the vents. I pulled the dash apart and followed the vacuum lines as far as i could but there was no kinks, pinches, or anything to stop the vacuum. I don't really understand the whole vacuum side of the system but from what I could tell, everything was ok.

The last issue is that when the fan is on 3 or hi, even without air con switched on it will operate for around 30 seconds before the fan stops all together and we have nothing on any setting. The relays were brownish in the centre and going on advice off this forum I replaced the relevant relays (think the blower fan, and blower fan inhibitor). Bought three relays from Sprints (who either sold me the wrong ones or all three are faulty - they were Narva). I have swapped some relays that were the same around and believe it may have fixed the fan issue, but not 100% sure yet.

I have been comparing our car to my parents car which is a series 2 vy v6. Did the series 2 have a much better air conditioner / air flow?

I will pretty well try any advice anyone gives me, don't have the cash to take it back to an air con specialist, so I'd appreciate any help.

Thanks everyone

 

[Black_Bug]

I have just read this thread...
http://forums.justcommodores.com.au...-not-cold-been-regased-compresor-working.html

Which mentions that the heater tap may not be closing off?
Can anyone tell me how to check the heater tap is closing? - when i checked the evaporater core it was hot, even though the a/c had been on.

 

[Greasy Hands]

airflow not switching would be either leaking vacuum actuators or no vacuum getting to system at all - I had this problem when i got my car (series 2 v6) and changed the actuators, problem solved.
testing them involves more than just looking at them - you need to apply vacuum to the ports and check for correct operation and leaks in the applied state, if the leak is big enough it wont apply at all.

Hot water valve remaining open could be a failed hot water valve vacuum actuator or again no vacuum getting to it, if i remember correctly the default position is open.
blower motor cutting out could be its internal thermal overload cutting out prematurely - indicating the blower motor may have reached end of life, its full of junk or its cooling airflow is restricted.

 

[Black_Bug]

Where abouts are the actuators located?
I can hear a hiss when it changes between all settings, except for recycled air. I can no longer differentiate between re-circulated air and fresh air (re-circ air blows a bit harder?).

So it probably wouldn't be a heater tap issue as much as a vacuum issue? I couldn't find any issues last time but maybe I didn't dig deep enough.
Is there a vacuum tank somewhere on these cars? My VS has a large one under the LHS headlight but am unsure where these ones are.
Is the tiny box next to the fan motor under the glovebox the vacuum tank or is that something else?

 

[Black_Bug]

Bit of an update, I have fixed a few issues but the air on max cold & a/c on is still only a few degrees cooler than air temp, and is very humid.
I have fixed the fan cutting out issue, which ended up being a bad relay.
I have checked out the vacuum issue and the actuators are function correctly and the air is switching to the desired vent. Also the heater tap arm seems to be going in when its on max cold (I think I read the arm is vacuum operated).
So, if someone can correct me if I’m wrong but could the issue be that even when the max cold is selected and the a/c is on, the heater core is still getting hot coolant which is heating up the air as if I have selected max hot on the dial. When this hot air hits the evaporator it is unable to cool it sufficiently as the air has been heated by the heater core already. So as it passes through the evaporator and out the vents into the car the air is only partially cooled as it was pre-heated, explaining the not so cold, humid air?

Meaning, the heater tap cannot be shutting off coolant flow to the heater core?
Meaning the heater tap arm that is closing is not sealing off flow, so the heater tap may need replacing?

So I guess my whole a/c system is fighting itself.

If someone can confirm the above it would help me out so much.

 

[Nut Kracker]

A very feasible explanation Black Bug.
Even a very small amount of hot water getting to the heater core will cause warm air to come through.

There are 2 hoses from the heater tap to the heater core.
I'm not 100% sure, but I believe only one of the hoses should be hot when the heater tap is in the off position.
If both are hot, this means that hot water is circulating through the heater core.
Maybe someone else can confirm this for me.

You could try disconnecting and joining the two heater hoses together, so they by pass the heater core and see if that makes a difference.

 

[iChris]

also check your a/c drain isn't clogged. if it is, that could also explain the humid air.

 

[Black_Bug]

thanks guys.

Is the a/c drain out the bottom of the evaporator core? If so that is clear.
That's not a bad idea to bypass the heater core, the only problem would be I would have to drain the system of coolant first?

I picked the local air con specialist's brain before (where i took my car before) and mentioned I have no idea how this stuff works but he said bring it in and they will give it a check for free since I just spent a heap of money but thinks I would probably be right that there is coolant circulating though the heater core all the time.

You would have to drain coolant before bypassing the heater core?

 

[Nut Kracker]

No you wouldn't.
You will loose some coolant (not much) doing this. It's just a matter of topping it up.
If you the A/C specialist is willing to do this for free, I'd take full advantage of his offer.

 

[Black_Bug]

He did say I can hang around while he does it so if he doesn't try it himself I might mention it