Removing A/C unit to replace evaporator

[LarryM]

My recent attempt to R&R my A/C blower without removing the entire evaporator box didn’t go well. So it looks like I’m stuck taking the whole thing out after all. I’ll also be replacing the evaporator core (now leaking…) and expansion valve (preemptively). Parts are on order.

The removal of the handbrake console, upper console, and HVAC control panel are all clearly outlined in Bentley and in some threads here, but beyond that it’s a little unclear to me how much more work is involved in extracting the A/C unit. There’s no complete writeup that I can find, and there seems to be some disagreement as to whether removal of the dash is necessary. I can see where that would require a lot of additional work.

So what are the additional steps I’m facing to remove the entire assembly?

Also, what are the correct o-rings needed for the evaporator and expansion valve? They’re not listed on RealOEM and according to my parts vendor they’re not listed in any BMW reference material either.

Will appreciate any help!

[SlickDizzy]

I was able to remove mine with the dashboard in place. It’s tight, but there’s room.

I don’t have any specific tips as it seemed pretty straightforward to me once I had it all apart and was looking at it. I guess the trickiest part was elaborately lifting and pulling on the evaporator box in order to lift the drain out of its hole in the transmission tunnel and delicately remove the whole assembly.

As far as the o-rings, just buy one of the $10 A/C o-ring kits from RockAuto or whatever for a 535i, it will have every one you need and some extras.

[Mike W.]

I did my heater core which first required removing the A/C without removing the dash also. It can definitely be done. I don't recall the details, it was just kind of take things apart until I got to it.

[jhh925]

As far as the o-rings, just buy one of the $10 A/C o-ring kits from RockAuto or whatever for a 535i, it will have every one you need and some extras.

Great info! I'm still a few months away from putting my AC back together, but this helps a lot.

Related question: RockAuto offers kits by GPD ($12), Four Seasons ($16) and UAC ($21). Any thoughts on relative quality between those three? Thanks.

[SlickDizzy]

There is likely no difference, in fact I wouldn’t be surprised if they all ultimately come from the same rubber factory and are just boxed up and branded in different places.

[LarryM]

OK, I guess I need to ask a more specific question regarding the removal of the evaporator box. Hopefully somebody here has done it recently and remembers.

Once I remove the radio, center and upper consoles, move the HVAC panel aside, and remove the insulator blanket, I see a there are a couple of screws holding the evap box to the floor. Once I remove those screws and disconnect the A/C lines where they attach to the evaporator, will I be able to lift the evap box up out of the drain hole in the floor and pull it out? Or are there other things I need to remove or disconnect?

I have a new blower, evaporator, and expansion valve, and am trying to determine if this is a job I want to attempt myself. I've never worked on A/C systems before but I'm willing to give it a go as long as I don't have to practically disassemble everything under the dash.

[SlickDizzy]

Once I remove the radio, center and upper consoles, move the HVAC panel aside, and remove the insulator blanket, I see a there are a couple of screws holding the evap box to the floor. Once I remove those screws and disconnect the A/C lines where they attach to the evaporator, will I be able to lift the evap box up out of the drain hole in the floor and pull it out?

Yes. Just did mine again last week while pulling the dash.

[LarryM]

Well, that's good to hear...as long as I don't have to also pull the dash. But it doesn't sound like it's necessary.

One thing I'm concerned about is cracking any of the delicate plastic ductwork when I'm removing the evap housing. When I've got it unbolted and pry it up to clear the floor drain, is it best to tilt the TOP of the housing towards the REAR of the car while pulling it out?

[SlickDizzy]

No, because the intermediate piece that connects the evaporator housing to the rest of the ductwork will be seated on both ends at the top. Once you’re clear of the drain, you need to rotate the bottom towards the back of the car, which will allow you to slide the top part down and out of the intermediate piece.

[LarryM]

Got it! Thanks Desmond.

[BRRV]

This is just my .02¢ .. but to me pulling the dash is absolutely not a big deal, and you can do it in under two hours. Pulling the evaporator box and the plenum for the two systems is, in my view, much harder with the dash in. Pulling the evap box out by the drain is a lot easier and you don’t wind up forcing anything or breaking the drain..

Granted, I’ve done it a few times, so I’m experienced, but the ease of not worrying about breaking something with the dash out and lots of room is a comfort.

[LarryM]

I finished this job a couple days ago and just want to point out something that makes removing and installing the evaporator box much easier.

The thing that makes this process so difficult is the fact that you have to lift the evap box high enough so that the drain will clear the hole in the transmission tunnel before you can rotate the bottom of the box towards the rear of the car. It's a very tight fit made worse with a layer of carpeting, some wire bundles beneath the carpet, and a thick layer of sound insulation glued to the floor. Although I got my evap box out successfully, I was concerned about breaking the fragile plastic ductwork or the drain tube, and so I was very careful. I think releasing the "suitcase latches" which connect the intermediate piece to the ductwork helps by giving an extra "pivot point" during removal.

Once I got my evap box out, using some shears (NOT box cutters!) I merely cut the small area of carpeting between the evap box and the shifter, and also trimmed away a small section of the sound insulation below the carpet. CAUTION: As I noted, there are a couple of wire bundles beneath the carpet so you want to make absolutely sure you're not cutting through those! If you do, you're in for a world of hurt!!!

This gives you an additional 3/4" or so of extra clearance which makes removing and installing the evap box less of a challenge. Just separate the carpeting, slide the wire bundles out of the way, and you have more room for sliding the evap box in and out of the drain hole.

Note that I removed only my A/C unit and not the entire heater assembly, so if you're replacing your heater core then maybe removing the dash is a better option.

[BRRV]

Yea, I think I’d read this somewhere, probably here. You’re right about the heater core: it’s what I had to do, which is the reason I defaulted to pulling the dash. I’m glad you got it done at any rate.

And I have a bad back, so I’d prefer getting the dash out of the way rather than practice my contortionist moves. (Besides, I have an E38 for that.. replacing the glove box struts or the interior air filters is worse, as there’s surprisingly little room in the foot wells.)

[Ohmess]

I just pulled my A/C box and wanted to comment on a couple of the suggestions here. First, forget the idea of releasing the "suitcase latches." There are three of these along the back of the box that cannot be accessed with the box in the car.

I ended up cutting through the carpet and insulation just in front of the evaporator drain. My drain was hanging up on the carpet. I split it right down the middle and created a channel for the drain to come out. As noted above, there is wiring below the carpet so I lifted the carpet/insulation and used a sheet metal shears to cut. This provides another 1/2" to 3/4" of clearance for the drain.

One other hint, I used a bungee cord from the rear view mirror to hold the wiring up and out of the way.