Need Some HVAC Advice 2003 Suburban

[Fitz98]

I have been having an intermittent problem with my 2003 Suburban AC for years now and really want to get this resolved. I do plan to keep it for a while, so don't mind to invest 1k to 1.5 k to get this working properly.
I am thinking of just replacing everything due to age of the vehicle and not being able to isolate the problem, plus I have a code for the air intake door actuator. This is a real pain to get to, so if I was to remove the dash to change the actuator, I would probably do the evaporator and heater core at the same time. I would rather not remove the dash, but I am not sure what position my air recirc door has failed, maybe it is open letting outside warm air into the mix.
The other thing I don't know is how much oil is in the system. I have had it serviced a few times and I think they usually add dye and/or oil when they do the service. Don't know what has been done before I got it at 66k miles.
So just replacing the compressor, accumulator and condensor, I would not know how much oil to put in without risking overfilling. Starting from new would give me an empty system.
I have replaced the fan clutch and the 2 Ambient temperature sensors with GM Original parts.
It works fine on most days less than 75 degrees, but will not blow super cold on warmer or humid days.
It seems like it comes in waves, where sometimes it blows cold, sometimes just cool, and sometimes warm.
The clutch is part of the problem. When it blows warm/hot, I can tap it to get it to engage. Could this explain a "cool" but not cold condition?
It would be nice to not have to open up the system if I don't have to, and just replace a clutch.
It has never been great since I got it and does not do well on hot days at idle. Changing the fan clutch did not help.
Alos do not get much improvement after getting it serviced, a little less clutch disengagement, but does not make it as cold as I feel it should be.

 

[chemman]

With rear AC the system takes 11.00 ounces of PAG 46 oil, and 48.00 ounces of R-134a

Without rear AC, the system takes 8.00 ounces of PAG 46 oil, and 25.50 ounces of R-134a.

The above data is from the 2020 Four Seasons Refrigerant and Oil Capacities guide.

I would not be surprised if all of the HVAC actuators (blend, mode, recirculate, etc.) did not need to be replaced. The total number of HVAC actuators will depend on if your HVAC system is manual, automatic, front and rear, front only, etc.

Perhaps @Chris142 can share some insight on this.

Good Luck!

 

[Gyro Gearloose]

I bought a used 2003 Silverado that had similar problems. The AC never did get really cold and even less so if the outside temperature was hot or the humidity was high. After checking through everything we concluded the problem was a failed outside air intake door actuator that had the system constantly pulling in hot humid outside air.

The outside air actuator is indeed under the dash cover and is also buried under a piece of ductwork. But there are youtube videos that show how to remove the dash cover, and it isn't that difficult or that much work once you know how to do it. And rather than disassemble more of the dash to get the piece of ductwork out, the pro tip is to just cut out the segment of duct over the actuator. It's fairly thin plastic and easy to cut. Replace the actuator and reseal the duct with some good quality duct tape and you are done. The right side blend actuator is also in that area so you might want to consider a preventative replacement on that while you are in the area with the cover is off. Since replacing the actuators really isn't that difficult of a job and no where near the disassembly required to replace an evaporator, I think I would try doing the actuators first and see how much improvement you get from that. I'm sure it will help some.

In looking at some parts diagrams in the past it looked like GM used slightly different HVAC systems on those vehicles depending on year, model and trim etc so YMMV, but that was our experience on a 2003 pickup with left/right manual temperature controls.

 

[vwmaniaman]

My 05 Yukon is acting the same way. Rear AC is ice cold but the front is bad. It is a common problem on those HM vehicles

 

[atikovi]

You're just wasting time and money throwing parts at it until you hook up a set of gauges to see what the system is actually doing.

 

[Chris142]

It's pretty hard to over oil a system that large. You really have to add a lot of excess oil to do so. A few ounces extra won't hurt the cooling , the ac clutch has a shim to adjust the gap. Remove the center bolt and pull the outer hub off, remove shim and remeasure the gap which should be .018-.028. I prefer them on the tighter side but finding a shim can be tough. I have a bunch I took from scrap compressors .if you have a door thats not working correctly that can definitely be a problem. Try pinching off a heater hose to see if cooling improves.

When you remove a component you drain the oil that's inside it and measure how much oil came out so you can add new oil. If replacing parts and you want to start over all new flush the old oil out of the lines and parts you are reusing to start with a known amount of oil. Use brackleaner and nitrogen or filtered shop air.

 

[Fitz98]

It's pretty hard to over oil a system that large. You really have to add a lot of excess oil to do so. A few ounces extra won't hurt the cooling , the ac clutch has a shim to adjust the gap. Remove the center bolt and pull the outer hub off, remove shim and remeasure the gap which should be .018-.028. I prefer them on the tighter side but finding a shim can be tough. I have a bunch I took from scrap compressors .if you have a door thats not working correctly that can definitely be a problem. Try pinching off a heater hose to see if cooling improves.

When you remove a component you drain the oil that's inside it and measure how much oil came out so you can add new oil. If replacing parts and you want to start over all new flush the old oil out of the lines and parts you are reusing to start with a known amount of oil. Use brackleaner and nitrogen or filtered shop air.

Thanks for this advice.
My gap is a little difficult to read. .021 seems to fit well with just a little friction, but not enough to move the feeler gauge when spinning the clutch.
I can force an .030 in with only a little effort.
I have started taking my dash apart to get to the fresh air intake door and actuator. I think it is open, since I have taken out the climate control unit and could still feel some air coming in with no fan on while in motion. (My scan tool tells me there is a code for this and my live data shows no change when I activate the recirc button).
What are your thoughts at throwing a new clutch on this along with the new actuators to get blending issues resolved? Is a new clutch something that would be practical to do on the vehicle without opening the system, or if while I have the dash apart, just replace the components with new GM Genuine components. As stated before, I don't mind throwing some money into the AC if I can get it working properly and efficiently.
Also, do you fill each component with oil, or just the compressor and the compressor will distribute where it needs to go?
Is brackleaner a typo?

 

[Fitz98]

You're just wasting time and money throwing parts at it until you hook up a set of gauges to see what the system is actually doing.

I agree with this, but I also feel like I am wasting money, because each time I take it for a 150.00 service, they put gauges on it, vacuum it, fill it and still no change in the intermittent issues. They say that is as good as it can get with all the stuff I keep inside (It is my work vehicle). I don't buy that. At the vent when controls set to 60 on auto, sometimes it is cold, sometimes it is cool and sometimes the clutch has troubles to engage at idle or in hot humid weather. I really do wish it was as easy as taking it to a mechanic and they can diagnose with gauges. Another mechanic said it could be multiple issues, which I do believe is the problem here.

 

[Chris142]

I use brake cleaner to flush systems. Don't bother with a new clutch on an old compressor. I really need pressures to diagnose it better.

 

[dumkid]

The a/c should be ice cold except when idling in hot weather. In hot weather at idle the fan won't move enough air to keep the a/c cold on these Chevys. You probably have a recirc door issue if it isn't ice cold with the vehicle moving. Also most a/c clutches should be between 15 and 30 thousandths, and yours sounds like it's at or slightly under 30 so I would take out the smallest shim in the a/c clutch and see if that brings it down to 25 ish thou. On an a/c cluch you want less gap for better grip but still enough gap to keep it from dragging.

 

[Fitz98]

When measuring gap, should the gap be measured with the max amount it takes to force the feeler gauge into the gap with friction, or should it be measured so the gauge slides freely with only a little friction.
The differential I am coming up with is 9 thousandths between the 2 different methods.

 

[dumkid]

It should be a medium amount of friction. Enough that the feeler gauge doesn't fall out if you let go but not a lot of force. So it should slide easily but still have a bit of friction.

 

[Fitz98]

Took the dash apart today to get access to the actuators.
The air intake actuator and the heater blend actuator that are both in hard to reach places in the dash are now accessible.
Both actuators seem to be significantly out of range in one direction. I think this is part of the problem with my air intake door.
Here is what has me scratching my head. They are both out of range by the same amount in one direction only, but the heat blend actuator works on command and the actuator will stay in range when hooked to that door, but be out of range when not installed, the air intake actuator will only cycle when I turn off the car and turn it on again. As it is going through its initial range test it does everything it is supposed to do...one time only.
I swapped the 2 actuators and got the same results, no change. They are the same part number.
When I use my scan tool, I can control the blending door actuator, not the intake actuator. When I do a recalibration with the scantool, they both do what they are supposed to do.
I am leaning towards the intake door actuator being out of range will not allow the climate control unit to communicate to it. Wouldn't the scantool bypass the climate control switching command and command the module directly?
Another part of me is thinking it is a bad climate control unit.
I have ordered a new GM Genuine actuator from Amazon 1 day shipping. 137.00...ouch. I would be foolish not to change both of them while they are accessible. (As mentioned, both are out of range and one is starting to make the squeak squeak noise while moving).
I hope it is not the climate control unit. The only originals I can find are on e-bay. I am assuming all from junk yards and no telling if they work properly or not. Afterall, I would think mine is working just fine, it is getting power and lights up. Knobs are a little finicky. The air recirc light comes on when I press it.
The new ones are chinese or Dorman and are 269.00 with terrible reviews and bright lights.

 

[Fitz98]

Does anyone know what I should be looking for at the actuator pins for power on the air intake door actuator?
My test light illuminates on 1 pin only, even when I press the recirc button on the controls.
This might help me determine if I have a wiring problem or a control problem...unless the power signal from the automatic control unit is dependent upon the actuator being within range.

 

[Fitz98]

The new actuator solved my intake air recirc door and the communication is back between the climate control unit and that actuator.
Did not need a new climate control module.
It's amazing how much colder the air is when it recirculates and does not blend in the outside air.
Replacing the 2nd actuator in that area tomorrow and then start putting it back together.
Next I will tackle the clutch so I can get it to kick on more consistently.

 

[dumkid]

Here in Arizona if you don't have recirc on your a/c will blow 110 degree air. With the a/c off it's 130 and with recirc on you can get the vent temperature down to 70 (the car will still be like 90 inside

 

[Fitz98]

I use brake cleaner to flush systems. Don't bother with a new clutch on an old compressor. I really need pressures to diagnose it better.

You mentioned not to bother with a new clutch on an old compressor. Is there a mechanical reason, or is this a cost reason, since the compressor is already old?
I have still yet to remove a shim to tighten the tolerance to see if that helps. One previous post in another topic someone suggested the coil may be getting weak as well.
Since I need to remove it anyways to remove shims, why not put on a new one for 125 to 200?
Rock Auto AC Clutch
This one from Amazon has all the new clips (not sure it is worth the extra 50.00 just for those).
Amazon AC Clutch

Or I could by a new compressor for 200 to 300.00 and pull the clutch off and keep the compressor for the future, if the clutch does not fix the problem.
I am just trying to avoid opening the system and getting into a much larger project if it is just a clutch.

Also, is it practical to think about doing this while on the vehicle? Looks like I have some working room if I take off the fan and fan shroud.

Knowing myself, if I am going to drain out the system to replace a compressor and accumulator, I would probably replace everything else for a few hundred more while I was at it before refilling. (Not the evaporator though) At this point, I would need a lot more time to take apart the rest of the dash to get in there. I am hoping to start putting the dash back together to get my vehicle back in service.

 

[dumkid]

A clutch might be worth it if your compressor doesn't sound or act worn (no funny noise through a screwdriver to the ear with a/c running, good pressure, doesn't feel weird/crunchy if you spin it by hand)

 

[repairman54]

I've had slipping clutches overheat the front seal on the compressor and leakage from the seal down the road. I just change compressors now.

 

[Fitz98]

AC Pressures