No AC on 2003 Suburban

[MASTERBrian]

The AC was blowing cold yesterday on several trips, then towards the end of the day everything changed and it only blew hot air and it's about 100*+ outside.

I hooked up a DIY gauge kit but it didn't seem to accept the freon, so I stopped. On Friday I plan on taking the truck to a friend that is AC certified to have him look it over and hook his gauges to it, but curious if anything I should check in the meantime.

I pulled and looked at the fuses, not the relay under the hood though, and all looked ok. I did not ohm the fuse to insure, might do that in a few. I do question the climate control switch as it looks like maybe it is grimy looking. Is there an easy way to test this?

My friend mentioned maybe the belt was thrown as they are common issue, but it looks intact and is spinning and isn't that old, maybe 20-30k miles.


****I'll add in the fall I had issue with no heat and that turned out to be clogged heater core, I had the system flushed and they said it was pretty bad and might need it again to clear it all up. Any chance that issue could have returned and that it's that time again? Or would that mainly affect the heating cycles?

This also affects both front and rear systems, the heat loss issue earlier was only the front heater core, so the rear system remained working. The blower works fine, I think all actuators are operational. It did seem at times as though maybe some cool was trying to come on, but it wasn't strong like normal operation, just maybe some cool. Hard to tell when it's that hot out.

[MASTERBrian]

I do question the temp blend door, BUT wouldn't that affect only the front or the rear, depending upon which switch and NOT both?

[greasemonkey]

When you say it started blowing "hot", was it blowing hot like the heat was actually turned on, or just hot as in the system was set on vent and the AC was not on?

[MASTERBrian]

Originally Posted by greasemonkey

When you say it started blowing "hot", was it blowing hot like the heat was actually turned on, or just hot as in the system was set on vent and the AC was not on?

It was just blowing hot! I actually am actually not sure at that time of day and with the outside temp it was it would have mattered.

I did get it figured out though, turned out to be a bad relay in the under hood fuse panel.

[Ski-me]

Many times it can also be one of your actuators. For my 2004' there are three main ones in the dash.

One on top of the heater box, one on the bottom side of heater box and one at the air inlet (side of heater box). All three are Part number 89018365

The one on top of the box is the most difficult to change out.

These are common problems and if you haven't changed them, they may be due unfortunately.

https://smile.amazon.com/Genuine-890...words=89018365

[greasemonkey]

Originally Posted by MASTERBrian

It was just blowing hot! I actually am actually not sure at that time of day and with the outside temp it was it would have mattered.

I did get it figured out though, turned out to be a bad relay in the under hood fuse panel.

Glad you got it figured out. I've had a handful of actuators fail on me, and they always went to full heat. It didn't sound likely you would have every actuator fail simultaneously and go full heat mode, but, well...
Thank you for following up with your solution. This will help someone later down the road, I am sure.

[MASTERBrian]

Originally Posted by greasemonkey

Glad you got it figured out. I've had a handful of actuators fail on me, and they always went to full heat. It didn't sound likely you would have every actuator fail simultaneously and go full heat mode, but, well...
Thank you for following up with your solution. This will help someone later down the road, I am sure.

Wondering if one or more actuators failed was a concern and part of my initial trouble shooting, but like you say unless they all failed it wouldn't explain no cold air. I also was wondering about the head unit, but again wouldn't explain why no cold I the rear because I do believe the front controls and actuators are totally separate from the rear unit. Correct me if I'm wrong.

[Ski-me]

Originally Posted by MASTERBrian

Wondering if one or more actuators failed was a concern and part of my initial trouble shooting, but like you say unless they all failed it wouldn't explain no cold air. I also was wondering about the head unit, but again wouldn't explain why no cold I the rear because I do believe the front controls and actuators are totally separate from the rear unit. Correct me if I'm wrong.

There are separate actuators in the back too. Had a case where up front was nice and cool, but the rear was throwing hot air. On the plus side, the actuators are very easy to change back there, but I also had to replace the brain controller unit too. Still cheaper than the dealer but that was a little spendy to get.

But at 174k now, truck has a nice HVAC system with a few replacement parts.

Rear Actuators are the same: 89018375 ACDelco (x2)

Rear Controller: 15-73506 ACDelco

[68c10airstream]

Just a quick ac check with your hand to see if the ac is fully charged. With the system running (compressor on) take your hand and feel the a/c accumulator (receiver drier). This is the silver can about 5" in diameter and about 12" high mounted at the firewall. If the system is fully charged, heater fan working, feel the top dome and then feel as close to the bottom as possible. If the top and bottom are cold = fully charged. If the top is warm and bottom cold,= low on charge.