e30 24v Swap AC not blowing cold *enough*

[agent]

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.

Yep, this was my experience as well. Calculating how much r134 refrigerant to charge an empty/vacuumed system with, we came up with 1.7 lbs. That's equal to 775g - right in the middle of the range mpowerful posted.

[dude8383]

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'.

I would recommend running that in addition to your aux fan... that would be super optimal IMO especially considering the temps you guys are seeing lately!!

[r4esh]

I would recommend running that in addition to your aux fan... that would be super optimal IMO especially considering the temps you guys are seeing lately!!

In that case are you suggesting keeping the stock (or higher flow rated aftermarket) 'pusher' fan and then adding "the secondary" as a puller on the radiator side?

[dude8383]

In that case are you suggesting keeping the stock (or higher flow rated aftermarket) 'pusher' fan and then adding "the secondary" as a puller on the radiator side?

Yep, a puller on the radiator will definitely help ya :up:

[sweet3]

Although you have had the r134 conversion, r134 does not work efficiently with the original condenser. The original condenser was designed to work efficiently with r12. The only true way to have your AC blow cold again will be to install a parallel flow condenser.
I now get temps around 45 degrees blowing through my vents.
I am only using the original pusher fan for the AC along with an electric puller fan mounted on the radiator for the engine.

[r4esh]

Slight update on the secondary issue– the 24v AC Idle Bump:

Per this thread, "MC Hammered" (thank you!) posted what sounds like a decent fix. Note that pertains to a "MS41.1" OBD2 DME.

For us OBD1 (413 & 503 DMEs) swaps the pinout will be slightly different, but the relay concept should still work.

IF I understand this correctly, essentially: Running ground to Pin 16 (obd2 cars) triggers idle bump. But we don't want this on 'all the time', only when AC is activated. The relay grounds that pin, while supplying +12v power to pin 19 (obd2 cars) to kick on the compressor.

As I'm looking at the OBD1 (2.5L for my harness/dme) engine management wiring digram I see this for the pin out:

- AC Switch : Pin 64 Violet/Gray
- AC Comp CTRL : Pin 48 Black / Blue
- AC Pressure Signal : Pin 65 Black/Gray

So am I right to say that for OBD1 cars this relay is to ground Pin 65 and +12v to Pin 64?

[DesertBMW]

E30 has early and late condenser. Late condenser has bigger piping and is good enough for 134a, AUX fan is a must.
Amount of 134a will depend on climate. For southern Arizona 775g is too much. Most shops use data that is for mild climates and usually overcharge the system in AZ.

People who are very smart think they know everything about e30 tend to overlook the most obvious. E30 does not have fresh air filter so evaporator may be half plugged up with junk reducing the efficiency. Rain drain is old and not closing up anymore so little bit of hot underhood air is getting into evaporator. Heater valve is not working properly so heater core is always hot heating things up inside. Flap gaskets are old and not sealing properly, hot air from hot heater core is getting into cold evaporator area. Hood gasket is old or hood is not adjusted properly, not sealing and hot underhood air is getting into vents.

[r4esh]

E30 has early and late condenser. Late condenser has bigger piping and is good enough for 134a, AUX fan is a must.
Amount of 134a will depend on climate. For southern Arizona 775g is too much. Most shops use data that is for mild climates and usually overcharge the system in AZ.

People who are very smart think they know everything about e30 tend to overlook the most obvious. E30 does not have fresh air filter so evaporator may be half plugged up with junk reducing the efficiency. Rain drain is old and not closing up anymore so little bit of hot underhood air is getting into evaporator. Heater valve is not working properly so heater core is always hot heating things up inside. Flap gaskets are old and not sealing properly, hot air from hot heater core is getting into cold evaporator area. Hood gasket is old or hood is not adjusted properly, not sealing and hot underhood air is getting into vents.

Interesting insight... Right now I have a NEW late model condenser. I also installed a new blower fan and swapped to a crackless dash about a year ago and thus had the opportunity to "clean things up" while they were apart as well as new seals around the heater core, etc. I'd like to think my setup is in 'better shape' than other's and it is preforming very sub-par.

@desertBMW I have no idea on the weight of r134a they used, but you'd suspect my system is overcharged?

For me to swap to a parallel flow + recharge the system is likely going to end up costing me at least ~$300ish. I'm not quite prepared to jump into this, but if/when I do, I'll report back to this thread to speak to the impact (if any).

[Luke_M]

From my experience you're definitely on the right track with a big fan and more efficient condenser. I've had my ac blow lukewarm air simply from having the fan separating from condenser approx 1" (mount came loose). Same thing happened when I messed with a "non ac" set of kidneys. I didn't think it would make much of a difference but it definitely does.

If you're willing to try it yourself you can get some decent gauges and a vacuum pump from harbor freight for around $150. Ebay has some as well. Freon from ebay is super cheap too.

I managed to do mine and it's working great in this humid 95 degree weather.

[r4esh]

Slight update on the secondary issue– the 24v AC Idle Bump:

Per this thread, "MC Hammered" (thank you!) posted what sounds like a decent fix. Note that pertains to a "MS41.1" OBD2 DME.

For us OBD1 (413 & 503 DMEs) swaps the pinout will be slightly different, but the relay concept should still work.

IF I understand this correctly, essentially: Running ground to Pin 16 (obd2 cars) triggers idle bump. But we don't want this on 'all the time', only when AC is activated. The relay grounds that pin, while supplying +12v power to pin 19 (obd2 cars) to kick on the compressor.

As I'm looking at the OBD1 (2.5L for my harness/dme) engine management wiring digram I see this for the pin out:

- AC Switch : Pin 64 Violet/Gray
- AC Comp CTRL : Pin 48 Black / Blue
- AC Pressure Signal : Pin 65 Black/Gray

So am I right to say that for OBD1 cars this relay is to ground Pin 65 and +12v to Pin 64?

Anyone have some insight on OBD1 swap idle bump. I've searched to my hearts end and don't have a very definitive solution to this and I'm not quite comfortable enough with the above^ to go 'fishing'.

[m3boost]

this is the condenser you need.. its for 134a and is a direct fit for e30

https://www.autohausaz.com/pn/64538391509NIS