Yikes! Looks Like I need a New Expansion Valve

[Broncos]

My new to '87 635csi was sitting for a few years and I noted it was converted to R134. I was hopeful yesterday when I noted that my AC clutch was engaging and thought I might be a bit low on freon. I slowly added some proper r134 and found that I had some hissing behind the glove box which points to the expansion valve, as I have rear ac, my understanding is that there is a rear expansion valve that is rebuildable -seemed like the rear wanted get cool but nope. Off to the pros - I might get lucky with a complete evacuation of the system and thorough vacuum but I kinda doubt it. If it turns out to be the expansion valve, might as well rebuild the whole system, add parallel condenser, updated compressor, drier, flush lines, etc - has anyone here had to do a expansion valve recently? if so, how nightmarish to access it? Thanks!

[Jubilados]

Doing the whole system, the expansion valve is easy, since you’ll have everything apart already.

[Broncos]

How hard is it to get to the front expansion valve?

[sansouci]

I eager to hear that answer as the dash might have to come apart

[Broncos]

Here is my plan, going to verify with an AC Pro - I am going to evac system, disconnect hard lines and do a complete line flush -what comes out should be interesting. I am not going to keep oem condenser up front, it received some rash from old radiator when fan pitched into rad so what I am going to do is find a parallel line condenser which is supposed to really improve upon the r134 efficiency. I will replace the receiver drier unit, hopefully I can find the right unit for my car as it has the rear ac unit. The Bosch wing cell compressor was originally an r12 compressor and now has had r134 through it -who knows if the conversion was done thoroughly, possibly not so will most likely fit a Sanden unit set up for r134. I am hoping the line flush will thoroughly clean out both expansion valves alone with the lines and evaporator so that along with other new components, I have half a chance of getting working ac. Can any of you reccommend a Sanden unit and is there a unit that has the right bracket for an easy bolt in transition? Thanks

[sansouci]

I am about to do a compressor replacement. My A/C pro and I will discuss which Sanden to use: 5 or 7 cylinder. I am also replacing the receiver drier. We'e keeping the TXV and original condensor and fan. He says the performance improvement of a cross flow isn't that significant. Maybe if we were in AZ or FL it would be worth it.
I will post what compressor and mount we chose.

[Broncos]

please do, thanks Sansouci!

[Jubilados]

I used the Sanden 5 piston, it’s been great. I looked at the 7 piston also, but I don’t recall why I went with 5 instead. There was a reason, but I can’t recall. (Although I think the 7 is fine also).

There’s several different bracket styles, they all work. I think the LC Wylie is the best, though.

I took my evaporator out to flush it, and was glad I did. It was clogged and took a lot of cleaner, water pressure and flow to get it 100% clean. r12 and 134a don’t mix, and clog up when put together. So if an r12 system has 134 in it, there’s a good chance it’s mucked up. (Because the reality is very very few really clean out the r12 when converting to 134). The only way to be sure is clear out everything. If it is clogged, anywhere, your new system will be a waste of time.

It happens all the time, read the AC conversion threads from people who do “90%” jobs, then are disappointed when their output is 60 degrees.

[Broncos]

Thanks! Many of the flushes mention that the expansion valve can be flushed while still in the line, (hope this is true) but yes, the condenser should be removed for separate cleaning or just replace altogether with a more efficient parallel condenser after all the flushing has been achieved properly. Completely vac lines would make sense to remove any traces of moisture so you are starting dry, new oil, new refrigerent, etc after that. Make sense? I have never internally flushed an evaporator but have shot special foam cleaner up the evaporator drip drain and yes, a ton of crud comes out which definitely helps the evaporator operate more efficiently. I have an '83 Dodge truck with r-12 that makes ice cubes. I cut through the evaporator housing with a hole saw, I centered the blade first with the center bit first and grooved the hole to be cut with the blade, then removed bit and cut through cautiously (man I was nervous doing this!) I ordered a large 3 inch firewall style plug so I could plug up housing after the cleaning process so I would always have a clean port to use whenever I wanted to clean the evap and of course be able to reseal that opening. I will mention that on my Dodge, the housing is completely exposed so easy unlike our 6 series cars, there was maybe a inch of clearance between housing and evaporator but I did not know this at the time. I can shoot coil cleaner in there, and then rinse with warm water using a garden style sprayer.

[Ralph in Socal]

Unfortunately the dash needs to come apart for access to the expansion valve. There was a hack of cutting the housing to gain access but many have unfortunately pierced the evap coil during the process. Best to just suck it up and do it the right way.

The e24/28 evaporator coil is separated into 3 different zones. 3 capillary tubes come off the connection joint with the expansion valve to feed the 3 different zones. It is the 3 capillary tubes that get clogged up. Likely clogged up one at a time as the system will still provide cool air but not as cool as when all 3 zones are functional. I've experienced several cars where all 3 tubes become clogged. System is fully charged but provides no cooling.

Apart from a new coil, the only real solution is to remove the evap coil and flush out the 3 capillary tubes. I've used brake cleaner with the straw to clear out each tube. Brake cleaners methanol and acetone components are highly volatile and gas off when pulling vacuum before charging the system.

I'm terrible at taking pictures when working. Please try to be better at it than I am and provide some pictures if you do go there. Good luck

Ralph

[Broncos]

I heard a hissing behind my glove box after filling the other day and upon depressing the schrader valve on the low port the next day noted no pressure . . . . this points to a perforation in the evaporator I believe which means new evap, valve, etc. Now I need to find a good sticky on removing center console, etc in order to access the evap. This is where I wish this car was much older (60's) and I was installing a vintage air unit . . . . all that plastic and fun . . . As my system is apparently now empty, I will most likely, via the low pressure port, add some air to see if I can duplicate that hissing . . it never ends does it? Btw, trying to find a diagram of what the ac line/components circuit looks like for the dual circuit cars (rear ac) cannot find it on realoem? What am I doing wrong with real oem as nothing pops up for e24 when I put in the last 7 digits of my vin? Weird! Thanks

[Ralph in Socal]

Try this link. Part way down to a post by Hefewiezen (Rainer.Steinbauer), he describes the dash panel removal

viewtopic.php?t=2465

Ralph

[Broncos]

Thanks Ralph!

[Broncos]

Pulled vacuum today . . . . oh boy, I have a sizeable leak and It is pointing to the evaporator so at this point, will need to pull console to get at the damn thing and of course, a new condenser (parallel type) compressor, expansion valves, receiver drier, the whole shebang . . . time to bone up on rebuilding the whole system.

[Broncos]

so realistic question - my console is removed, how much more work in front of me to remove evaporator and expansion valve?

[Jubilados]

Not much.

[Ralph in Socal]

AC box should be directly in front of you and fully exposed. Take apart freon lines and take good pictures of electrical connections. The box needs to elevate to clear the plastic drain nipple at the bottom. That's the difficult part

Ralph

[Broncos]

Thanks Ralph!