The Detailed E30 R-134a Conversion Thread/DIY

[danix]

Thanks for this writeup and thread. I confess I didn't see it in time.
Local well regarded corner garage was doing an HVAC special ($25 plus freon and parts).
Dropped the car off, they went through it (88 325i convertible, automatic).

They said it checked out and would hold pressure, would need to add R134A fittings (4 of them) and refrigerant. I gave them the goahead.
$25 quickly went up - $20 for dye, $80 for 2.15lbs of R134A, almost $60 for the fittings, $50 labor charge for installing fittings. With tax, total so far $245.25.

Now, not complaining - they seem straight and told me to try it this way first vs replacing a bunch of stuff and that most cars seem to get by just fine without replacing.

Here's the problem and where I need your advice...
They said the AC fan is only coming on at low speed, and that unless I am driving the car at speed, the AC will not work right and the compressor is at risk of blowing up.
Tech checked the fan (ok), relay (ok), and looked at high and low pressure switches.

Tech spent the morning looking and is convinced that there is an intermediate pressure switch he can't find, according to Alldata. I don't think there is one.

More data:
high side pressure 225-350psi
low side pressure 30-60psi
center duct 58 degrees at ambient of 75 degrees

Thoughts, advice? I'm going to check Bentley and see what the diagram shows.
Thanks :)

[danix]

Did some testing of my own
Checked all fuses.
Checked all relays (K1 and K6).
Jumping wires at the temp sensor (3 wire switch) result in both low and high speed on the aux fan.
Only weird bit - according to one diagnostic page, with relay K1 out, and AC on, there should be voltage at socket pin 86. I don't have any.

Tested the Bosch low voltage resistor - I have 6.5v on one side of it (the side with 2 wires) and 0v on the other but I'm starting to think that side is ground.

According to one thing I read, the aux fan high speed comes on ONLY when the radiator temp switch is engaged. Anyone know at what temperature that is, and if I can check that temp in the onboard computer?

[jeffnhiscars]

I believe that switch is set to 90c but what you were told is incorrect. The aux fan comes on at low speed whenever the ac comes on. High speed comes on from that temp switch in the radiator independent of the ac (unless you jump the resistor which is what your tech was suggesting)

I'm guessing you got 6.5 volts on the high speed lug because it was the low speed side that was energized (so you should have had 12v there) and the resistor cuts that in half to create low speed since the fan is technically a single speed fan. If your fan wasn't running at that point your fan is bad, the hot lead from the resistor to the fan is bad or the ground wire is.

Personally I jump my resistor but that really only helps in traffic and at low speed when there isn't much air flow running through the condenser. At higher speeds it should not matter especially since your comprssor is running at higher speed

Did some testing of my own
Checked all fuses.
Checked all relays (K1 and K6).
Jumping wires at the temp sensor (3 wire switch) result in both low and high speed on the aux fan.
Only weird bit - according to one diagnostic page, with relay K1 out, and AC on, there should be voltage at socket pin 86. I don't have any.

Tested the Bosch low voltage resistor - I have 6.5v on one side of it (the side with 2 wires) and 0v on the other but I'm starting to think that side is ground.

According to one thing I read, the aux fan high speed comes on ONLY when the radiator temp switch is engaged. Anyone know at what temperature that is, and if I can check that temp in the onboard computer?

[danix]

Arg, reply didn't post so have to retype it all.
Shorter version and thanks for the reply:

- my aux fan comes on low when the AC is on
- didnt hear high speed fan but didn't let it sit there and get hot either
- AC is great at speed, not as great in traffic. This appears to be normal behavior yes?
- Some people bypass the resistor to force high aux fan all the time (again when snowflake is engaged or temp sensor calls for it). I believe this requires switching the 7.5A fuse for a 30A yes?

Sounding like this is all perfectly normal behavior, I think.

[jeffnhiscars]

That would be correct except I think the stock low speed fuse is 15 not 7.5. Either way it should be a 30

[danix]

Right, 15A for fuse 3, the low speed relay, 30A fuse 18 high speed relay, 7.5A fuse 19 (aux fan) and 30A fuse 20, AC and aux fan.

Told the mechanic I think it's working as designed and he got all "oh fine, go ahead and blow up your car, don't blame me." At a standstill or low speed, he says the pressures will get too high.

Took a closer look at the Alldata info mechanic was looking at. It all sounds correct except for this part:
"There is also an intermediate pressure switch fitted to the receiver/dryer. This switch, which is normally open, closes when pressure exceeds 260psi. This energizes the high speed relay and runs the aux fan at high speed."

It appears this is what he says doesn't work (and can't find). Going to recheck the diagrams to see if it exists or if this is misinformation.
- Edit - it appears on the E34, there is an intermediate pressure switch. None exists on the E30 as far as I can find.

[spiftacu1ar]

I'm also looking for another condenser option. Anyone know of one?

EDIT:
After reading this entire thread I found that most people were saying to use the Nissens one on autohausAZ. Aamzing what reading the whole thread will do for you :-)

Awesome, thanks!

Here's the link if anyone needs it:

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

[efficient]

Anyone know if using acetone to clean the pipes and the little radiator underneath the dash is ok?

[e30 gangsta]

Hey guys quick question. I bought the compressor adapter kit to run a Seltec 488-45021 which is a tm15. I called up my local ac supplier and they told me that they do not carry the tm15, but that they carry the tm16. Which supposedly is the same thing but it will cool the car better they said due to more cooling capacity/power consumption.

They also said that they had sandon 4663 compressor that is the same as the seltec, but I've read and heard that they leak and have issues/ they aren't as high quality as the seltec.

So my question is if you had to pick a compressor which one would you go with? And which is the correct mounting type ear or direct?


seltec tm15
seltec tm16
sandon 4663

Thanks.

[Klug]

I'm not sure what Sanden bracket I had- but if it is close, it should work. You have to modify it anyway, so you should be alright. Check out my Sanden DIY in my sig for pics

[Chubtone]

Does anyone have a source or a spare APG compressor bracket for m20? I am gathering all the parts for this conversion and that bracket seems to be NLA.

[glucklich21]

Have you tried giving APG a call? Even if they don't have it anymore, maybe we can get a group buy going assuming they still have the files.

[jeffnhiscars]

Does anyone know an alternative to the condenser listed on the first page? As JinormusJ said, they seem to be out of stock everywhere.

Amazon was the last place I saw them.

[clarkson]

I have bought 2 of these, one for my M3 and one for my touring, seem to work well:

http://www.ebay.ca/itm/381227819688?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Oh and I also successfully rebuilt my E30 M3 Bosch Behr compressor with new carbon shaft seal... that was fun ;)

[Z2TT]

Hi Guys.

2 Questions.

1 - Any links / part numbers of Parallel flow condensers for E30

2 - How to test if both low and high speed fan settings work - does pressure switch trigger speed difference?

Thanks.