I replaced my drier today and vacuumed the system for about an hour and a half. The system held vacuum ok so I decided to charge it but I couldn't get any refrigerant into the system. I borrowed these R134a adapters from a friend and he told me he thought there might be a problem with the low side. When I blow into the high side adapter and screw the red valve all the way down, air begins to pass through the valve. When I do this with the blue valve, air never does pass. Sounds kinda obvious that there's a problem with it, can anyone confirm?

Another issue I had which I thought was strange and made me question my entire approach was that I never did get the aux fan to come on. I jumped the hi/low switch to get the compressor to kick on but I thought that would make the aux fan come on too. This is a new truck to me and while I know the aux fan works because it spins with 12v applied, could there be a problem with the HVAC temp controller not powering the relay that energizes the aux fan? And could that be affecting the system drawing in the refrigerant?

 

The Aux fan does not immediately come on when you turn on the AC.

 

Thanks Best. Took 40 min to drain the can, and I think most of it went out through a poor seal. Aux fan never came on though.

 

those connectors are tricky. Lubricate them with penatrating oil and make sure they click all the way down than lock it in place. You have to really push them in to the high or low side fittings on the disco.
Or else your getting a fake reading on your guages

 

The worse AC lines I have ever had to mess with were on both my 07/08 Hummer H3's! You'd remove the cap and be staring straight at this piece of rubber. If the gauges were cheap or were pushed on really hard you could damage the rubber seal inside. After I had both my H3 AC systems serviced they seeped for the rest of the entire time I owned them....... The caps had o-rings on them, but over time you'd see the black residue all over the cap, and line = it was seeping. At least the LR lines used the normal and more robust schrader valve looking seals for their service ports.

I do all my own repairs but when it comes to AC work I take it to my buddies shop with the $$$$$ Snap-On AC Machine.

 

Couple updates to this. I bought a new pair of adapters and was able to get two 12oz cans of R134a into the truck. Air blew cold, hallelujah. The low side pressure could have been a little higher for my liking but with an ambient of about 76-ish, the air out of the vents was frigid (can't find my thermometer) and it wouldn't take any more refrigerant. I was trying to get the last ounce in out of a 30lb can but no go. I'll have to wait for truly hot weather to see if I'm fully functioning or just limping along. No history of the air in this vehicle, maybe the compressor is weak.

The part that concerns me is that the Aux fan still never came on. In all, it's been about 2.5 hours of AC run time and the condenser fan asn't come on once. When filling the system I jumpered pins 3 and 5 of R117 relay and the fan ran while I was charging the system. Then I replaced my jumper wire with a known good relay, still no fan. I was under the impression that whenever the AC was engaged the fan would operate. Best4X4 says no and I'll take him at his word. If anyone would know, I'm fairly certain he would. I checked the ETM and will trace out the circuits to make sure the wires carrying the switched ground from the ECU and the ATC is good. Beyond that I'm not sure what to check. I swapped in a known good ATC prior to jumping out the relay today so I know that part should be engaging the relay when it's called for. Does running for so long with no Aux fan sound like normal behavior? Is it just not the right condition for it to kick on? Not hot enough?

I also noticed tonight that my clock doesn't illuminate, never noticed that before so I can't say if it ever did but will swap in a spare to see if it lights. Pretty sure it should. The HVAC buttons didn't light either but I can't remember if they ever did. The display itself lights but none of the buttons themselves did, is that normal?

 

You can get a light bulb for the clock on Amazon for a couple bucks. Pretty easy install - pull out the clock and you can access the bulb. I’ve seen kits for the HVAC lights as well but haven’t done them personally so can’t speak to how easy it is. The buttons should light up just like the rest of the stereo buttons.

For your condenser fan, often times they seize due to lack of use. I think they’re not supposed to come on unless either (a) the AC is running and ambient temperature is >78°F or (b) engine coolant temp is >212°F - so if you haven’t hit those, it’s behaving as designed.

I’m also fresh off an AC restore and my fan is totally locked up (I can’t even manually spin it) and all the bolts that secure it are completely rusted and unable to be removed. However, my temps are pretty much normal so far. I’m sure AC performance would be degraded in traffic but truthfully even though I’ve bought a replacement off eBay (~$80 for a used one), I have no idea how to install a new one without fabbing a new bracket. And removing the old bolts gives me pause since I don’t want to try and drill through them and then poke a hole in my condenser and have to replace it, so I guess I’m going to play it by ear.

 

My fan runs when I jump the relay so I know it's not a fan problem. And that means the feed to the switched side of the relay is also good. Something is not pulling in the relay when I thought it should be. I'll monitor for operation in higher temps and see what happens. I read the Electrical Library's operational description and while it mentions "correct conditions" must be met, it doesn't say what they are. 78° as the trigger is a good piece of info, it definitely wasn't that warm out.

When conditions are correct, the ECM provides the earth path which energises the cooling fan relay coil closing the contacts. The feed from fuse 5 in the engine compartment fusebox passes through the cooling fan relay contacts and from the fusebox to the cooling fan motor on a BN wire. The feed operates the cooling fan motor which is connected to earth header C0018 on a B wire.

I was I have a spare clock and ATC so I'll put those back in and see if they light up. Thanks for confirming they should.

Regarding your fan being rusted on, I have a spare set a of brackets from an 03 if they'll help you. It sounds as if you can't get the brackets off the clips, as opposed to the fan off the brackets, but my parts truck should have everything you'd need aside from the condenser itself so let me know if I can help.

 

The fan mounts on four brackets to two horizontal bars that run across the front grill area - you can see the bottom two brackets in this picture:


Thanks for the offer - those bars are also the mount point for the receiver/dryer assembly. There are four screws that hold on the condenser fan, and I don't think a single one is going to come out on its own - I soaked with PB blaster but they're just disintegrating once I try to put a socket or a screwdriver on them. I think my best bet, if I were to replace it, would be to cut the plastic on the old fan to remove it and then attach a new one - I guess I could use like JB Weld to attach it where it needs to be, or I could take an approach like the picture above and mount it with zip ties.

From what I've found, there are people out there who just drive around with a seized condenser fan - really as long as the engine temps are OK then I guess there's no harm except for maybe slightly reduced AC performance. It's not like I'm located in TX where it'll regularly be 100F - my temps, based on at least my initial try yesterday @ about 80F, are normal (though my fan clutch was more engaged than normal and the fan was louder and pulling more air). I'm curious about how much air that little electric fan really moves, anyway. Maybe I'm able to fully offset it with the Dorman 620-112 fan and severe duty fan clutch, which undoubtedly moves more air than the stock cooling setup.

 

Yep AC Efan will only come one once the ambient temps get above 85-88F if I'm not mistaken. Otherwise it will stay off unless the engine is above 210-212F then the Efan will come on to help cool the engine.

On a D1 the Efans come on the second you turn on the AC. The D2 is totally different due the electronic HVAC unit vs the D1 manual setup.