Rear AC not cooling

[desertrat67]

I just got the blower working in my 90, but I am not getting any cooled freon(or whatever refrigerant it is) to the lines at the back of the truck. It looks like the lines are just spliced off the lines to the front System.

Is there a switch in the system somewhere?

Anything I might be overlooking?

 

[dbreid]

On mine (which works, because I had it flushed, put in a new compressor, drier, etc), the only switch is whether or not you have the fan/blower on. There's a switch on the dash that says Rear A/C (which I also replaced) with runs the rear blower motor (yep, I replaced that tooo..... sensing a pattern?).

When I turn the AC on from the front, it just always works the rear, but you choose whether to run the fan or not.

As far as I can tell, there isn't another switch? Unless theoretically the front switch also hits some sort of cutover? I guess now that I think of it, I never crawled back there to test if it was chilly without the fan, but I believe it just always works.

I started this post thinking I'd be helpful, but now I am not so sure if I might not just be being more confusing.

-Dan

 

[desertrat67]

I didn't mean a manual switch, I meant one that is in the AC lines somewhere.

It looks like there might be on the coils at the actual unit in the rear though I am not sure. I looks like a thermostat type thingy(has a long wire running off of it strapped to the inlet line).

And the front AC works great.

 

[throttleissues]

I didn't mean a manual switch, I meant one that is in the AC lines somewhere.

It looks like there might be on the coils at the actual unit in the rear though I am not sure. I looks like a thermostat type thingy(has a long wire running off of it strapped to the inlet line).

And the front AC works great.

That sounds like the expansion valve, and that "wire" would be a capillary tube. The temp of the tube changes the pressure in it, and that controls the exp valve orifice. I'll have to turn mine on and see if the lines get hot/cold. I know my front A/C doesn't work well unless the rear is turned on.

 

[desertrat67]

Thanks. I would appreciate it. I will go mess with it again later. I am redoing some wiring under the hood now and have both batteries removed.

 

[throttleissues]

Well, I ran mine with the front A/C on and the back off, and the lines near the right rear tire got warm/cold, as in one was warm and one was cold. I also looked at the one I have torn apart and didn't see anything that would actually prevent flow back there when turned off, just the expansion valve. If your exp valve is plugged, however, the lines would feel the same temp (as each other) and the rear won't cool down.

 

[desertrat67]

If your exp valve is plugged, however, the lines would feel the same temp (as each other) and the rear won't cool down.

That is about how it is. I only ran it for about 30 secs to a minute once we got the blower working. I am going to go out when the wife gets back to run it again and see if anything happens

I found I have a small crimp in the larger line going to the rear. It isn't pinched completely, but it is slightly distorted. I hope this isn't a problem. I can go get a new line from the junkyard. There are at least 5 subs with rear air out ther. Got to love Texas.

Priced the expansion valve: $45. might grab a couple from the J-yard though. Probably spend $20 for the valves and replacement line.

I'll keep updating.

 

[throttleissues]

Priced the expansion valve: $45. might grab a couple from the J-yard though. Probably spend $20 for the valves and replacement line.

Just be really careful with the capillary tube in the exp valve, as they're really fragile.

 

[desertrat67]

It looked like it was. I have to see if the on post craft shop has AC tooling so I can save a buck evecuating the system and then refilling with what they took out.