The Detailed E30 R-134a Conversion Thread/DIY

[jeffnhiscars]

You're not going to get the same performance at idle,or low speed since there just isn't enough air moving through the condenser to dissipate enough heat. The easiest aid if you don't want to upgrade the fan is to jump the resistor so it runs on high all the time. You'll hear it somewhat at idle but it's not a bad trade off.

the other thing is that absolute vent temps are not an objective measure since there are so many variables that will effect that...is vehicle speed, ambient temp, humidity, recirc vs fresh air intake etc etc. measure the differentIal between return air and output. Residential differences in the 17-20 degree range are considered ok as reference but then houses are 100% recirc.

last point is that the probe that pokes in to the evaporator from the driver footwell should cut off the compressor at 37 so I the system should in theory never ice up. When I stilling it in a new evaporator do not use the probe to poke through the fins. It's soft, will bend and f your not lucky it will block your blend door so you can get full heat AMHIK

[nick.cbr]

You're not going to get the same performance at idle,or low speed since there just isn't enough air moving through the condenser to dissipate enough heat. The easiest aid if you don't want to upgrade the fan is to jump the resistor so it runs on high all the time. You'll hear it somewhat at idle but it's not a bad trade off.

the other thing is that absolute vent temps are not an objective measure since there are so many variables that will effect that...is vehicle speed, ambient temp, humidity, recirc vs fresh air intake etc etc. measure the differentIal between return air and output. Residential differences in the 17-20 degree range are considered ok as reference but then houses are 100% recirc.

last point is that the probe that pokes in to the evaporator from the driver footwell should cut off the compressor at 37 so I the system should in theory never ice up. When I stilling it in a new evaporator do not use the probe to poke through the fins. It's soft, will bend and f your not lucky it will block your blend door so you can get full heat AMHIK

Yeah that's what I was getting at: the only next step I have while being as OE as possible is looking into the aux fan airflow situation. I'd like to try the newer style fan that has more blades and perhaps a more efficient design but that's probably giving it too much credit. ECS have an aftermarket one that seems to be a direct fit to what's in there now that I'd like to try.

Absolute fair point on vent temps I don't think you can compare temps without some reasonable controls. Like I wouldn't say my car runs 40*F in New Mexico when its 105*F 40% humidity and expect to compare someone in Virginia where it's 95*F and 100% humidity. I guess where I was going with vent temps is, from my testing, my E46 which has a perfectly functioning cooling and AC system will sit between 38-40*F all day long on the freeway on any given day I've ever ran it this summer (which is regularly). The E90 (also a pristine cooling system) runs a bit warmer, usually 41-43*F but both of these cars can hold those vent temps or stay very near them freeway or idle. The key here is that I've tested these things very regularly now in high heat (95*F+), moderate heat (85*F or so), high dew point etc. and to be honest, they're pretty damn consistent vent temp wise. Meaning: they'll consistently show those same vent temps in any sort of heat where I'd consider using the AC. That said, I haven't tested in 65-70* weather and my testing was not by the book "scientific method."

So those more modern cars obviously have far more efficient AC systems than the E30 and it's apples to oranges but what I'm trying to ascertain now is how good was the stock system in the first place on the E30? To me, as the car sits, it will get into the high-50's or low 60's on idle... that kind of sucks. Please tell me R134a cars are not that bad? If they are, there's less reason for me to switch than ever. Like, I'd be damn surprised if that's how these things performed in 1989 straight out of the factory where they'll gain 15-20*F in vent temp from freeway to idle. No possible way they were that bad, were they?

It will be interesting to see what happens as I replace parts and come to a conclusion on wether R12a is viable in these cars. I mean, maybe the TXV isn't tuned as well as it could be for R12a? Is my compressor questionable? Is the condenser clogged and not efficient? Would switching fans improve performance? Does my dryer suck (I have have two new ones to play with) I'm sure nobody understands my logic which is fine. I guess I'm just not convinced you need to change all this stuff in order to get cold air. You can still get all the OE switches (high and low for the dual switch cars), dryers for old and updated cars, etc. I don't want to hack up my wiring and put in a parallel flow compressor unless that is truly the best way to get good AC performance. So I guess I'm going to be that stubborn guy that burns up a bunch of cash only to find out y'all were right.

EDIT: all my testing is done at low-ish fan speeds, with recirc on. E30 would be fan position 2 the E90 the 2nd bar and I'm not going to count the pixels on the E46 but you get the idea. Controlling for outside temp and humidity, the E46 and E90 have very little temp differential regardless of road speed (they also have fans that move some serious air on idle). The E30 has what I would consider too big of a differential.

Also, interesting note on the residential temp differential

I also forgot to mention that bypassing the resistor to run the fan on high was an excellent suggestion.

[jeffnhiscars]

I think you're right on the money as far as design differences between models go. The e30 is just not that efficient. Having said that I've had stock systems that were converted without any hardware changes (except perhaps the X valve) and they worked incredibly well. That does t mean I've ever tried to achieve the same results since HVAC is part science and part art.

Each of the changes you're considering should offer an incremental improvement. When to get off the merry go round depends on your budget, your patience, your skill level and your seat glands :).

the low hanging fruit is the resistor and a clean condenser (PF isnobviospisly better & not expensive), but the big kahuna is 100% a dry and tight system. While I hate repeating myself, I can't say this enough times....the only way to know you've reached this target and are no longer just spinning your wheels, is with a micron gauge. A clean system w a new drier, deep vac as close to 500 microns as you can get then the 32oz charge. From there you can decide if any other changes make sense.

[mtony]

I need to replace my converted Hi/Low pressure switch connected to the dryer/receiver. Can I unscrew the old one without loosing refrigerant, or will I have to evacuate the system before I do that?

[jeffnhiscars]

I need to replace my converted Hi/Low pressure switch connected to the dryer/receiver. Can I unscrew the old one without loosing refrigerant, or will I have to evacuate the system before I do that?

Unfortunately you're opening the system to replace that so will have to recharge

[cory58]

I'm doing a partial upgrade to my 7/91 build date cabrio (can't call it a "conversion" because it's already running R134a), replacing pretty much everything under the hood but not touching anything under the dash. Can I use the lines that run through the fire wall to flush the evaporator without removing it (or the expansion valve) from the car?

Thanks, Cory

[jeffnhiscars]

Hey Cory. The expansion valve is a restrictive orifice by definition so doesn't lend itself to flushing and you can remove it without disturbing the evaporator. Just wondering why you're doing a flush on an already converted system. If it was working well and you're just updating components why not just replace the drier, top up the PAG (based on what you've replaced) and recharge ?

[cory58]

Hey Cory. The expansion valve is a restrictive orifice by definition so doesn't lend itself to flushing and you can remove it without disturbing the evaporator. Just wondering why you're doing a flush on an already converted system. If it was working well and you're just updating components why not just replace the drier, top up the PAG (based on what you've replaced) and recharge ?

Thanks Jeff. One of the AC hoses failed back in 2007-ish. I was still a maintenance noob back then and did not ask my mechanic any questions when he did the 134a conversion. It looks like he changed the o-rings but I have no idea whether he changed the oil or anything else other than the hose and dryer. This time I'm replacing the condenser, compressor, dryer and several of the hoses, so I thought it would be worth the effort to flush everything I'm reusing. What looked like dye also came out when I took it apart last weekend.

[jeffnhiscars]

He would have had to change the oil if he converted from r12 or it hold have reached havoc on your system but if you're swapping out pretty much everything a good flush is wise. Use the oil recommended by th compressor mfg (typically PAG 46) and do check if it's filled or not on arrival as some aren't. I'm assuming you know that 134 requires barrier hose and they we not all available new. I got some custom done by a firm in Jacksonville Fl quite reasonably.

It sounds like you don't have much confidence in the guy who did the conversion so you may want to make sure he also changed the X valve for an R134 specific valve.

Good luck and hope to bump in to you when we move back to NC next year.

[cory58]

He would have had to change the oil if he converted from r12 or it hold have reached havoc on your system but if you're swapping out pretty much everything a good flush is wise. Use the oil recommended by th compressor mfg (typically PAG 46) and do check if it's filled or not on arrival as some aren't. I'm assuming you know that 134 requires barrier hose and they we not all available new. I got some custom done by a firm in Jacksonville Fl quite reasonably.

It sounds like you don't have much confidence in the guy who did the conversion so you may want to make sure he also changed the X valve for an R134 specific valve.

Good luck and hope to bump in to you when we move back to NC next year.

Great advice. Thank you. Awesome news that you're moving back. Look forward to reconnecting.

Cory

[atmh]

Well, looks like I'll be going down this rabbit hole. I took most of the A/C system out of my car when I put the turbo in 15ish years ago, but now I'm a bit older and live in a bit of a warmer climate, and really want that sweet A/C. Since I'm basically starting from scratch, the whole system will be new and might as well make it R134a. Seems like this thread has almost every question I could ask, but, here's a few I didn't readily find!

ECS carries two Nissens parallel flow condensers that "fit" my car (an '84 325e). Any idea what the difference is between them?

Condenser 1:

https://www.ecstuning.com/b-nissens-parts/air-conditioning-condenser/64538391509~nis/

Condenser 2:

https://www.ecstuning.com/b-nissens-parts/bmw-e-30-82-93-condenser/64538391509~nin/

Question two: they also carry an R134a compressor. Any idea if this is just a refurbished r12 one with the correct seals, or if it's actually an R134a unit? Also mostly they're out of stock so maybe that's a sign of the times and hence why it looks like people are mostly getting creative with universal compressors and custom brackets...

Third and final question: I took out my aux fan all those years ago in lieu of an intercooler. To be honest I never had any overheating issues without the aux fan, but I also didn't have an A/C condenser. What do people do who have an IC and condenser? Just run with no fan? Find a low profile one that fits? Something else?

Thanks for the help!

I might piece the system together now so I can see how everything fits, but I'm not going to be charging it or test running it for a long while, perhaps years, while the rest of the car is built. In fact all I really need for now is the condenser and maybe an aux fan to make sure the IC fits.

[Striker01]

I'm down this rabbit hole already. I can't help with the condenser question, I ordered the one from the beginning of this thread and it fit and works well. I am on my second rebuilt original compressor, the first I noticed was bad before I installed it, the screen on the inlet side was only half there. The second I installed with a new dryer, expansion valve and rebuilt barrier hoses; had the system vacuumed and charged, blew cold but noticed oil leaking from the front of the compressor after a week of use. I am sending that one back this week and ordered the sanden bracket from Wylie and Co, along with a SD5H14 compressor. I got the bracket and new compressor for less than a rebuilt original and didn't have to wait three months for either to be in stock like I did for the second bad original. It will cost a little extra to have the hoses fabricated for the new compressor but I'm not willing to wait and see if the third time is a charm with a rebuilt compressor. Maybe I just had bad luck with the rebuilt ones but if I were you I would just get the newer style and pay to have hoses built, you'll probably want to update yours to barrier hoses anyway.

[atmh]

Thanks! Yeah it seems like the LC Wylie bracket plus a sanden compressor makes the most sense. The cost of the bracket plus the compressor is the same or less for me as a rebuilt (out of stock) compressor from ECS or FCP. Plus an improvement to the function by using an R134a compressor rather than a rebuilt R12 compressor. Plus the new hoses from ECS/FCP are extremely expensive, so it might not be more (might even be less?) to get custom hoses from an A/C shop. All in all seems like a win-win.

For anyone wondering LC Wylie has an actual website here (I avoid Facebook when I can, so I'd rather order via other means if possible) https://lcwylieco.bigcartel.com/

For my last comment: I *think* what I'm going to do is an electric fan conversion on the puller side, plus a bigger, custom-fit radiator for my turbo build. I will then shift the radiator and condenser about 1-2" closer to the engine via custom brackets. This should give me enough room to fit the IC plus a low profile aux fan. I think this path makes sense based on some of the threads in the Forced Induction section. Looks like the common refrain is "keep the clutched fan, don't bother with an electric conversion" but it seems like that's the best option for adding an IC up front. Very little room on my car, since I'm also adding an oil cooler and attempting to keep the "Type 1" front valence, which has the least amount of room / shortest overhang of all the e30 valences, as far as I can tell.

Will eventually post progress pics, but it's gonna take a while to get it all sorted. If I forget to update this thread it will be on my build thread, here: https://www.r3vlimited.com/board/for...o-resurrection

[Tzantushka]

Question two: they also carry an R134a compressor. Any idea if this is just a refurbished r12 one with the correct seals, or if it's actually an R134a unit?

If it's this one:

https://www.ecstuning.com/b-genuine-bmw-parts/remanufactured-a-c-compressor-r134a/64528385712kt/

Then it looks like a Bosch Behr Wing Cell compressor which is a R12 design probably with R134a compatible seals.
Stick with a Sanden wobble plate design built for R134a - that worked for me!

Will keep an eye on your build thread!

[atmh]

If it's this one:

https://www.ecstuning.com/b-genuine-bmw-parts/remanufactured-a-c-compressor-r134a/64528385712kt/

Then it looks like a Bosch Behr Wing Cell compressor which is a R12 design probably with R134a compatible seals.
Stick with a Sanden wobble plate design built for R134a - that worked for me!

Will keep an eye on your build thread!

Actually I had no intention of buying a compressor for ~$1300, lol. There are a couple out of stock for <$500. So a $170 bracket plus $150 Sanden compressor seems like the way to go.