e30 24v Swap AC not blowing cold *enough*

[r4esh]

Hi- the car is an s52 swapped e30 m3. Ever since the swap was done almost ~5 years ago I've felt the AC wasn't cooling properly- it blows cold air, just barely. When it is 100+* outside (thanks Arizona) the AC is practically in-effective.

It has a new e30 condenser & new e36 compressor. I took it somewhere locally to have the system evac & filled. They 'resealed both compressor fittings, resealed discharge fitting at condenser with new o-rings, added pag oil, dye, and charged the system with R134A.

I stumbled past this fantastic thread: The Detailed E30 R-134a Conversion Thread/DIY - which led me to question other elements in my systems setup:

• e30 uses "Tube & Fin style condenser" (pic of mine), though mine is 'new', would replacing this with a 'Parallel Flow Condenser' make a big difference?
• With the R134A do I need to change my "pressure switch"?
• With the R134A do I need to change my "receiver/dryer"?
• With the R134A do I need to change my "evaporater/expansion valve"?

I will be grabbing a diy can of R134a later to to check if its just low on refrigerant.

[Poopie]

parallel flow will help tremendously.

How is your fan set up? Are you getting ample cooling over the fins?

[r4esh]

parallel flow will help tremendously.

How is your fan set up? Are you getting ample cooling over the fins?

Here is a picture of my stock e30 fan & stock (but new) e30 condenser:



Do you believe a parallel flow condenser is the ticket? What about all the other things I listed?

[exhaust]

Yes to all except the drier. To my knowledge, the drier is the same for R12 and R134a.

R134a has different properties than R12 (I think pressure and weights?) so the switch, expansion valve and condenser all need to be changed. All easy work, the only pain is the expansion valve since it's in the lower section of the dash, attached to the evaporator.

[mpowerful]

I used a parallel flow condensor, stock pressure swtich, stock expansion valve, and stock aux fan setup to run on high (m52 swap). Ive done multiple e30 conversions (swapped and not) and in no case have found changing the pressure switch or expansion valve makes any difference. Wiring your fan to run on high and upgrading to a parallel flow will make all the difference in the world. 2 years on my personal swap blowing ice cubes with south louisiana heat indexes generally above 100.

[mpowerful]

Oh also the charge. I see your gonna add a can. I highly recommend finding a buddy with a nice gauge setup or a machine. Ive experimented ad nauseum with the charge on converted systems in e30s and despite the bmw technical bulletin listing 900g as the r134 charge the perfect charge really is somewhere between 750-800. Having an accurate charge (and add a couple ounces of oil) will go a long way.

[exhaust]

I used a parallel flow condensor, stock pressure swtich, stock expansion valve, and stock aux fan setup to run on high (m52 swap). Ive done multiple e30 conversions (swapped and not) and in no case have found changing the pressure switch or expansion valve makes any difference. Wiring your fan to run on high and upgrading to a parallel flow will make all the difference in the world. 2 years on my personal swap blowing ice cubes with south louisiana heat indexes generally above 100.

Interesting, I was under the impression that the switch and valve were completely necessary. Any reason that the conversion guides list them? Do they make any difference at all? (Genuinely curious)

[mpowerful]

I have read that some of the valves were both 134 and 12 compatible. So far as I can tell the ones I have changed had the same part number as ones that came out and i suppose the earliest ones ive worked on were 87s. Either way changing or not changing it hasnt ever mattered. I suppose maybe really early valves had a different orrificie or maybe they were afraid you could get the system clean enough without removing it and therefore just replacing as good measure. Same instance with switch. There was an earlier and later switch setup. 134 tends to run at higher head preasures. Again never made any difference to change the switch. Maybe only because ive ever run up against the later style switch setup.

[Poopie]

i'm having issues with the idle up when the compressor is engaged. Any tips? I'm running a 413 dme on a m50. i didn't do the swap. I'll pay for your flight up here to finish mine haha. No shops in the philly area i have contacted wanted to do it.

[r4esh]

@mpowerful, thanks for the insight here! My car is a late model (1990) m3. I just checked realoem and I show 2 different part numbers for the Expansion Valve, both of which are listed as R134A support. I'm also seeing the correct pressure switch as well. Perhaps thats a late model thing.

So based of this thread, it sound to me like all I'm after is a parallel flow condenser, might as well throw a more efficient fan on while I'm in there– then recharge the system and cross my fingers that it makes a big difference. (it was 115*F today in Tucson, AZ so needless to say I'm motivated).

Any recommendation on a (perhaps larger?) parallel flow condenser and a good (pusher?) spal fan? Does it make sense to do the drier while I'm at it?

-----

Secondary question I maybe should start a separate thread for:

When I turn on the AC I get the infamous idle serge, the car shakes, etc. Idle hops from around 500-800ish RPM. My assumption is that the DME isn't telling it to bump the idle when the compressor is engaged. I can't seem to find the thread now, but I read somewhere a while back of someone making a custom relay that tapped in under the glove box and would supply a ground somewhere when the ac was engaged. Any thoughts?

[dude8383]

The stock AUX fan should be more than capable of keeping things cool.

I've done multiple conversions as well and the parallel flow condenser does make a significant difference.

If you search around for the "idle bump" thread you'll find that some people have documented the procedure :up:

[r4esh]

The stock AUX fan should be more than capable of keeping things cool.

I'm running clutch fan delete with the lower temperature switch so my AUX fan is always running. Today it was 110*F (brutal) and with the AC at full blast it was practically doing nothing– and my temperature gauge was starting climb a bit above the middle mark.
I'm thinking (hoping) a SPAL fan may preform better than OEM and keep things 'optimal'.

[DesertBMW]

Why did you use E36 AC compressor? They are inferior compared to E46 compressor.
I got my M54 swap E30 with E46 compressor with 134a and my AC is ice cold today in 118f Phoenix weather. Most shops in AZ don't know proper measurement on how much refrigerant to charge. It has to be spot on.

[r4esh]

Hey, r4esh, what ever happened me supposed to get a swap tune for your S54 swap?
Why did you use E36 AC compressor? They are inferior compared to E46 compressor.
I got my M54 swap E30 with E46 compressor with 134a and my AC is ice cold today in 118f Phoenix weather. Most shops in AZ don't know proper measurement on how much refrigerant to charge. It has to be spot on.

You got me mixed up with someone else. I'm s52 swap. Hense the e36 compressor :) ... one day s54 maybe..

[DesertBMW]

You got me mixed up with someone else...

yeah I did.