The Detailed E30 R-134a Conversion Thread/DIY

[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

[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 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.

[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]

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]

I had a bit of a setback. I couldn't for the life of me get the low-side pressure to come up at all. Would stay around 5-8psi - high side was ~150psi. The vent temp was exceptionally cold but after 30-40 minutes of driving, the vent temps would start to increase to low-mid 50's (F). I'm pretty sure the evaporator core was freezing up (also noticed fan performance wasn't quite as good and sounded a bit different. Without being able to see in there, I'm just guessing. The thought is the thermal expansion valve (TXV) is hung up and not metering flow well enough which is causing very low temps but eventually ending in an ice-over condition. At this point I've ordered new hoses, TXV, o-rings, dryer, low switch, high switch and a new tube/fin condenser to get to a point where I know what I have. I'm also poking around trying to sort out the parts necessary to run through the compressor as well. There is a guy over on mye28.com that rebuilds them but I'd prefer to try it myself if I can.

My issue turned out to be a bad TXV. Replaced the TXV and charged with about 11oz of R12a from FrostyCool. Low side pressures came up to about 45psi which now seems high and 115psi on the high side which seems low. That said, vent temps are stable at 40*F at freeway speeds I can run for over and hour and the evap doesn't seem to freeze up as it will just run at 40*F. I haven't done anything else to the system other than change the TXV to a later R134 unit (Egelhof brand).

So now the issue is the car cannot maintain 40*F air at idle or low speed (30MPH or less). My entire cooling system is brand new (including viscous fan clutch) and the aux fan immediately starts to spin on low as soon as the AC button is pressed (or the recirc is on which is kind of odd). Obviously 40*F at idle in the drive thru is probably unrealistic for this system but I feel like it should at least do high 40's or low 50's on idle. It looks like my aux fan is one of the old style 5 blade units; wondering if I should try a newer version. I really don't want to go full hack and install a universal Spal fan though...

My compressor started kind of ticking as well... added a bit of oil as I've evac'd and recharged so many times now testing all this stuff so probably need to rebuild that now. Anyway, just posting my progress in case it helps anyone.

I should add that I don't really know what I'm doing/learning as I go.

[nick.cbr]

Is FrostyCool R12a the same thing as or similar to HC-12a? The FrostyCool web site says it's flammable but doesn't have an MSDS or ingredient list.

I'm not qualified to answer that question; it's essentially propane and isobutane and I'm guessing each company has their special blend. They're hydrocarbon-based and flammable.

[nick.cbr]

Would you mind linking the Amazon purchases for the rest of us?

# mineral oil
https://www.amazon.com/dp/B010294CQQ...roduct_details

# oil injector

https://www.amazon.com/dp/B01N95O7UZ?psc=1&ref=ppx_yo2_dt_b_product_details

# valve cores and tool
https://www.amazon.com/dp/B001MS51CG...roduct_details

# additional valve cores
https://www.amazon.com/dp/B00UC9ONRK...roduct_details

# vacuum pump
https://www.amazon.com/dp/B00UC9ONRK...roduct_details

# manifold gauges
https://www.amazon.com/dp/B07CZB3P4X...roduct_details

One note on the gauges: if I were to do it all over again, I think I would get the higher-quality Yellow Jacket brand gauges. I had no issues with the ones I bought and they do have a blow molded plastic case that seems to be decent.

I used some cheap digital thermometers from Harbor Freight for vent temps.

I bought R12a from a guy on eBay but ended up just buying a case direct from them as I knew I would be doing a lot of testing.

https://www.frostycool.com/copy-of-f...alent-3x-cans/

[AmosCake]

You don't fill it. SOP is to add 10cc for a drier or replacement hose and you can use a syringe to measure and push it in.

You insert the syringe through one of the ports the hoses connect to? Thanks for response

[jeffnhiscars]

You don't fill it. SOP is to add 10cc for a drier or replacement hose and you can use a syringe to measure and push it in.

[AmosCake]

how does one fill the new dryer with PAG oil?

[cory58]

Is FrostyCool R12a the same thing as or similar to HC-12a? The FrostyCool web site says it's flammable but doesn't have an MSDS or ingredient list.

[chouchoo]

This. I made zero changes to my hardware. Verified system held vacuum and charged with FrostyCool R12a that I got on eBay (I think it's a way better deal to buy direct from their website even though shipping is ~$19 though so I'd probably avoid the eBay seller). I was getting 41*F at the center vents on idle (fan on 2, recirc ON) and a consistent 33*F at cruise (at one point I saw 32.x*F). Ambient temp was ~70*F and very high humidity; waiting for the heat to come back to do some more testing but I expect some pretty good performance out of the system.

Per the FrostyCool website, I used 11oz of their R12a refrigerant to charge the E30 system that calls for 2.1lbs (+/- .05) of R12. For equipment, I used some manifold gauges, R134a conversion fittings and a two-stage vacuum pump - all off Amazon. I left my existing dual pressure switch setup in place as well as the stock expansion valve. I'm still playing with things so I'll report back with more concrete data on pressures and things like that. I thought I may have overcharged the system so I vented some refrigerant out and now I believe it's under-charged again as my idle vent temps went up to 52*F and cruise vent is 37*F. All of this is on factory R12 parts namely the condenser (fin/tube not parallel flow).

I had another E30 325iX converted to R134a about 10 years ago and that car performed admirably; however, I really think sticking with the R12 system (tube and fin condenser), replacing the dryer and all the o-rings is the correct solution for these cars. Based on my research, I'm just not concerned about running a hydrocarbon-based refrigerant either (a common argument against R12a). It is unfortunate that the EPA hasn't approved this as a replacement for R12 systems as it is better for the environment than even R134a (which is no longer in favor anyway as everyone is switching to R1234yf or whatever it is).

Would you mind linking the Amazon purchases for the rest of us?

[jeffnhiscars]

Jeff is probably right, but it would be just my luck to end up with a hose that's been sitting on a shelf since 1988.

The final bits of my AC that I replaced were the 2 hoses that go from the firewall to the evaporator (behind the glove box). They were NOS off of eBay from a seller in Israel. One was NLA and the other was dealer only, hence stupid expensive. The day they arrived I sent them to a hose shop who replaced the decades old new r12 hoses with barrier hose. $75 later it was done.

im guessing but I doubt you'll find NOS anywhere on the planet. Just sayin' :)

[AmosCake]

RealOEM shows part 1040 superseding the old R12 hose part number, which means 1040 will fit your car. Different situation for part 1051. RealOEM does not show a replacement for the R12 hose (part 4234) and that hose is specific to the M42, so you can't count on 1051 fitting your car. Unless someone with an M42 chimes in here, I would recommend going to your local dealer and asking the question at the parts counter. Up to you whether you buy the hose from them after they help you out (I would).

Yeah i searched that part up and its for verts and sedans but since its R134a compatible i checked to see if it would fit and according to ECS tuning it is compatible