Another HVAC Question

As I'm about to finish up some engine related things, my next direction will be the HVAC system. This truck has had a slow leak requiring a can of refrigerant from the day I purchased it new. All those years ago, I had a buddy detect the leak from somewhere under the dash. Basically said it wasn't worth messing with. So, up until a couple years ago, I was just adding a can of refrigerant. Two years ago, I attempted to add but I got some bad readings and backed off. I suspect the orifice tube or expansion valve may be clogged. The compressor seems to work, albeit it cycles on and off frequently. I did have it converted over several years back to R134.

To make matters worse, I have a blend door that I'm certain is messed up and the hot/cold slider is jacked. Last time I tried to make a temp adjustment it seemed a little stiff and then it just gave way with white plastics pieces falling out from under the dash....arghh. I've read up on the blend door.....what a poorly engineered design. So given all this, I need to tear the dash assembly out. While in there probably should replace the heater core too, assuming access is from that direction.

So, a few questions. Would you replace the entire AC system or the suspected parts? For just a little over $200, I can get a new compressor and component parts. This is Rockauto, Four Seasons Brand, which I've read good things on. This does not include the condenser, though it is recommended.  

My last question is in regards to the blend door repair. That cheesy door is still available for $115.....don't think so! I've read about repairing it with a hinge and even tape. I'm not all together against the hinge repair but am almost more keen on repairing it with some Gorilla tape. Thoughts?  

1 The evap core is in the engine bay right next to the blower motor and can be removed from there. There are a couple of studs with nuts and a bunch of bolts, I want to say 5.5mm or 8 mm heads that let the box split in half. If you were getting a freon leak in the cab, it was coming from the evap core as it is the only AC part in or close to the inside of the cab.

2 What pressures were off? If the pressure was to high on the low side that could be the orface tube plugged or the evap core could be covered with crud from being in there for 34 years. If the pressure is high on the high side, it might be that the condensor is partly plugged, the compressor is failing or the fan clutch is failing.

3 Pull the orface tube and look at it, if it has metal bits or shavings in it, change the compressor as it is ready to fail.

Hi Steve, thanks for the response! I can't remember specifically how my gauges read, it's been too long. I've been without AC for a couple of years now and just haven't been using the truck much so I could not justify the time for the repair. Knew the evaporator coil was the likely culprit but did not know you access it from the engine bay, which is good, I think. I'll pull that orifice tube and check it.

Thoughts on the condenser coil, can it be flushed? Seems I've read that 90 models have tubing that is too small and won't flush, what about our trucks?

Hi John, If you still have the orignal condenser, it is the coil type that can be flushed out. The after market style, it looks like a small radiator with several tubes that start at one tank and end at the other tank, then no. It has to be replaced.

old55pete wrote

There are a couple of studs with nuts and a bunch of bolts, I want to say 5.5mm or 8 mm heads that let the box split in half.

I want to say Ford used an oddball 7mm head on a lot of these fasteners

It's not 6~1/4" or 8~5/16" but in between.
And I can't get an 11/32" nut driver on it either.

Yes, Ford and Chrysler used a lot of 7mm head fasteners, The Chrysler stuff is usually machine screw style and used a lot on trim clips. Ford and the Dog, er Dodge I just worked on have sheet metal style, especially on the inner fenders.