Clogged AC expansion valve? (1 Viewer)

[RhinoRig]

Hey all,
I swapped out all the o-rings and swapped to 134a. The A/C is fully charged and but not blowing cold consistently. I put a manifold gauge set on it and the low side is almost drawing a vacuum and about 200psi on the high side, so coolant isn't flowing. FSM says it could be moisture in the system or the expansion valve is clogged, which is a bitch to get at. The manual says there could be dirt in the valve and to just blow it out. I can get a new one locally if needed. The only down side is that it's very difficult to access the valve and I want to make sure that is the correct course of action before opening that can of worms. Any one have experience with this?
Thanks!

 

[WyattEarp1918]

Hey all,
I swapped out all the o-rings and swapped to 134a. The A/C is fully charged and but not blowing cold consistently. I put a manifold gauge set on it and the low side is almost drawing a vacuum and about 200psi on the high side, so coolant isn't flowing. FSM says it could be moisture in the system or the expansion valve is clogged, which is a bitch to get at. The manual says there could be dirt in the valve and to just blow it out. I can get a new one locally if needed. The only down side is that it's very difficult to access the valve and I want to make sure that is the correct course of action before opening that can of worms. Any one have experience with this?
Thanks!

I’m doing that job today! What a bitch!!!!!

 

[WyattEarp1918]

I’m doing that job today! What a bitch!!!!!

So I’m all ears for help too

 

[RhinoRig]

Ive had the box out before and the entire dash had to be disassembled. I was terrified of busting 35yo plastic but it worked out. Don’t want to tempt fate again, but probably have to.

 

[WyattEarp1918]

We could not get that F’ing box out. We settled for cleaning the box out and cleaning the the condenser and cleaning out the drain tube. We replaced the compressor, receiver/dryer and the front thing in front of the radiator. All Denso except the receiver/dryer it was. AC Delhi.

 

[jellis]

If you swapped from R12 to R134a you need to clean the entire system to replace the Mineral Oil with PAG. Oils are not compatible between those two refrigerants and you will ruin your compressor in fairly short order (I learned from experience on this one). I now run R12a instead which is compatible with both oils, however I just recently finally broke down and cleaned out the entire system and it was worth the effort in increased performance.

 

[RhinoRig]

If you swapped from R12 to R134a you need to clean the entire system to replace the Mineral Oil with PAG. Oils are not compatible between those two refrigerants and you will ruin your compressor in fairly short order (I learned from experience on this one). I now run R12a instead which is compatible with both oils, however I just recently finally broke down and cleaned out the entire system and it was worth the effort in increased performance.

How do you get all the old oil out? Solvent of some kind?

 

[WyattEarp1918]

If you swapped from R12 to R134a you need to clean the entire system to replace the Mineral Oil with PAG. Oils are not compatible between those two refrigerants and you will ruin your compressor in fairly short order (I learned from experience on this one). I now run R12a instead which is compatible with both oils, however I just recently finally broke down and cleaned out the entire system and it was worth the effort in increased performance

 

[WyattEarp1918]

I stuck with R134a and used the special Denso oil (expensive) when I replaced my system

 

[jellis]

Yup. I didn't do mine initially but even with R12a which dissolves both I could tell there was a "slug" in there of different oil or whatever while viewing the sight glass. Compressor sounded weird when it went thru as well, so I decided to flush finally. Much better cooling, compressor doesn't even make a noise now.

This flush kit.

This flush solvent.

Tear all hardline connections apart, remove condenser, then flush each line and everything EXCEPT Compressor and expansion valves (don't flush across your heat exchangers they clog really easy, not much oil in there anyway). Also thoroughly drain your compressor for a long time, rotating often, to get out as much of the old oil as possible.

R134a will NOT circulate Mineral Oil properly and your compressor will seize (get ruined) from lack of lubrication. This will most likely take the form of the belt starting to smoke while driving down the freeway, and potentially shredding apart in your running engine. I've had both happen separately, it's really a fun thing to deal with in the middle of nowhere!

If you just put R134a in a previously R12 system, simply get it evacuated and put in R12a and don't bother flushing anything it's way easier. I use FrostyCool:
FrostyCool 12a Refrigerant "18 oz Equivalent" - 3x cans Replacement for R134a - https://www.frostycool.com/copy-of-frostycool-12a-refrigerant-18-oz-equivalent-1x-can/

 

[RhinoRig]

I’ll give that a go. But first, I think my expansion valve is clogged.
What if I blew some low pressure air into the low side and see if I can free up the valve? Trying to avoid the inevitable.
And I have no idea what compressor the PO has on this thing. Said it is a 2016 1HZ from Europe, so maybe PÁG? No idea. May be best to flush it and start fresh. Especially if I’m digging into the evap box!

 

[jellis]

I've redone my AC like 5 times in the last year or two. Very stupid. It's definitely worth doing right, once!