08 Denali Air Conditioning Frost

[tgui]

Its been *just* warm enough here (mid 70's) to use the AC. I'm seeing frost on the AC (condenser?). Is this normal? I know NOTHING about AC systems.

The AC blows DAMN cold!

I'm taking a long road trip soon and don't want the AC to fail.

 

[kbuskill]

That is the dryer not the condenser.... Your system may be slightly under charged causing the evaporator (the part that gets cold under your dash that the inside air blows across to get cool) to freeze up and subsequently the dryer which is bolted to the evaporator but its on the engine side of the firewall.

Check your freon level... If its low add a little.

If its not then the office tube may need changing.

The dryer should get cold and have condensation dripping from it but it should not be freezing up like that.... I'm guessing it is slightly under charged.

If you add freon I would get freon with the UV leak detector dye in it so if it leaks out again it will be easier to find the leak.

 

[tgui]

That is the dryer not the condenser.... Your system may be slightly under charged causing the evaporator (the part that gets cold under your dash that the inside air blows across to get cool) to freeze up and subsequently the dryer which is bolted to the evaporator but its on the engine side of the firewall.

Check your freon level... If its low add a little.

If its not then the office tube may need changing.

Can I get my freon level checked and topped off at some place like Autozone?

 

[tgui]

I ran the ac hard for a while. After parking for 5 min the thing melted and ac still was blowing cold.

 

[kbuskill]

How long had it been ran in the first pic with it froze up???

Autozone or the like cannot/will not check it but you can buy freon with a hose and gauge attached. If its not causing any problems then I would leave it alone for the time being.

 

[2011SSVHOE]

If it is blowing cold keeps you comfortable don't waste your money

 

[undy]

That is the dryer not the condenser.... Your system may be slightly under charged causing the evaporator (the part that gets cold under your dash that the inside air blows across to get cool) to freeze up and subsequently the dryer which is bolted to the evaporator but its on the engine side of the firewall.

Check your freon level... If its low add a little.

If its not then the office tube may need changing.

The dryer should get cold and have condensation dripping from it but it should not be freezing up like that.... I'm guessing it is slightly under charged.

If you add freon I would get freon with the UV leak detector dye in it so if it leaks out again it will be easier to find the leak.

Not the dryer, it's the suction accumulator. The dryer is on the high side of the refrigerant circuit. The suction accumulator is on the low side (which is what you're seeing).

If it's frosting up one or a combination of the following is happening:

1) low pressure switch has failed.
2) Cabin filter is totally clogged
3) evaporator coil is clogged.
4) dead/inoperable indoor fan motor

Don't try adding refrigerant or changing the orifice tube as this will only exasperate the problem.

 

[tgui]

I ran it super cold for a long time and it froze over to the point of no air blowing.

I stopped by a shop. Found it was low. The system was flushed? and dye was added. No leaks yet defected. They said a clogged orifice or bad switch were common problems too.

It works fine now but I'll be watching it like a hawk. Oh and no more frost.

 

[Fosscore]

Good info on this thread as we approach summer. My A/C is on almost daily now.

 

[2011SSVHOE]

Good info on this thread as we approach summer. My A/C is on almost daily now.

Yea no shit you live in the Sunshine state, Glad I live in the Moonshine state. Maybe we need a sticky for AC Issues or a separate section just for HVAC just my 2cents!!

 

[tgui]

Yeah a separate section might be nice. I had no idea where to ask my question.

 

[Miami-Dade]

Good info on this thread as we approach summer. My A/C is on almost daily now.

Mine has been on since I bought my Hoe last October..Even in the winter the sun is just plain nasty..Just IMHO.

97% of people here in South Florida never seem to drop their windows.

 

[tgui]

I did a 1.5 hour test with highway driving. I can get it to start to ice up if I put it on the coldest setting and lowest blower setting, which is dumb.

I'll stop by the shop again to see if I'm losing pressure.

 

[tgui]

Not the dryer, it's the suction accumulator. The dryer is on the high side of the refrigerant circuit. The suction accumulator is on the low side (which is what you're seeing).

If it's frosting up one or a combination of the following is happening:

1) low pressure switch has failed.
2) Cabin filter is totally clogged
3) evaporator coil is clogged.
4) dead/inoperable indoor fan motor

Don't try adding refrigerant or changing the orifice tube as this will only exasperate the problem.

1) - I have this on order. Will replace in a couple days.
2) - Already have a new filter
3) - Perhaps. These Yukons didn't come with filter from the factory. It has to be added in with a kit. I get quite a lot of air blowing through, so maybe not this.
4) - This fan blows good!

I had the system recharged and it was low, no leaks. It behaves better now that the pressure is correct. I'm betting on the low pressure switch. The air gets really cold before it freezes up something the low pressure switch is supposed to mitigate from what I gather.

 

[tgui]

I replaced the low pressure ac switch. Its hard to tell if it's helping. Ambient air was 65f, I set the ac to as cold as possible with lowest fan setting. I could just get it to start icing over. It's a stupid test and might cause any ac to freeze a bit. I mean who has the ac at the coldest setting, lowest fan, with seat warmers going on a 65f day?

I did still see frost on the accumulator.

I used a new one ring from advance Auto, lightly oiled.

Old out!

 

[tgui]

Back to the shop! It was freezing up again bad this morning.

This has to be the most boring thread I've ever made.

 

[tgui]

Fixed. You'll never guess....

It was my new HVAC controls. I'm not a pro. Supposedly new HVAC controls need a GM tech programmer to setup or it causes all sorts of issues like freezing up.

I'll deal with the old controls for a while.

Good news is that I have no leaks, new low pressure switch, new orifice and so forth.

 

[PG01]

Fixed. You'll never guess....

It was my new HVAC controls. I'm not a pro. Supposedly new HVAC controls need a GM tech programmer to setup or it causes all sorts of issues like freezing up.

I'll deal with the old controls for a while.

Good news is that I have no leaks, new low pressure switch, new orifice and so forth.

Really, that is f'in stupid....glad you figured it out

 

[tgui]

Really, that is f'in stupid....glad you figured it out

Yeah. It pisses me off. Live and learn.

No issues at all now. I can hear the compressor cycling on and off now. With the bad HVAC controls I don't think the compressor was cycling at all, hence the freezing.