BHW into Eurovan swap - AC question

[iwannajettatdi]

Finally getting things buttoned up... I have a question about the AC compressor and fan relay circuit. All manual controls, no climatronic in the van or donor car. 2002 Eurovan that had 24v 2.8 VR6 and an 01p auto, and 2004 B5.5 Passat donor car with BHW.

In the Eurovan, there is a relay 140 that is the AC control module, and a 214 relay for the AC clutch cut-off relay. The 214 cut-off relay is only for automatics in my wiring diagram (I am doing a manual swap, so don't need that, right?) It looks like the Passat has a cut-off control module as well, the dreaded relay 384, but it looks like that relay controls both functions that requires the two relays in the Eurovan. The Eurovan relay is 8 pins, the Passat is 6 pins. I can't find a TDI specific wiring diagram from what I downloaded from Erwin, just a generic 2000s Passat and one from a 1.8t.

It looks like pin 1/87 (sw/gr) on the Passat relay goes to the engine control module through the red 15 pin connector on the firewall housing.
Also pin 4 (br/li) goes to the cluster?



I'm confusing myself looking at the wiring diagrams, and I was hoping for some help from others that have swapped this motor.

The fan control relays and resistors from the van are all still in place. I know the fans work, because I can jumper them and get them to stay on whenever the key is on.

The wire from the Passat for the AC clutch is a gn/ge (green/yellow), and the clutch grounds to the engine block.

Do I need the gr/ge wire and/or the Passat relay at all?
Can I use the van's circuit for all my AC needs? Or would it be better to swap the van's wiring over to my Passat AC relay?
Does the BHW ECU need any input from the AC relay and/or the fan control system?
How do I connect the BHW ECU and the Eurovan fan relays so that they are triggered to come on and shut off at appropriate times with the load reduction relays for starting, on for AC/when it's hot out, etc?


I think I'm making this more difficult, but with all the wires floating around and visions of wiring diagrams in my sleep I'm going a little nuts.

Any insight?

Thanks.

Ryan

 

[Braddman]

I highly recommend you get an Alldatadiy.com subscription for the 2004 Passat TDI because it will help you enormously with the swap as they have all the diagrams and repair instructions.

I just checked the 2004 Passat TDI diagrams. The AC compressor clutch is switched on by the Climatic control module which I figure you will not be using. The 2004 Passat TDI does not use an AC cutoff control module

The BHW ECU is supposed to communicate with the Climatic control module but the engine will run fine without it you will just need to have fault code deleted in the program to clear the check engine light.

In the 2004 Passat TDI the rad fan get powered by either a high/low speed temp switch near the rad. Or the fan can run low speed from the Climatic control module. The ECU does have an output to the rad fan for after run. I don’t see the after run function really being needed. The ECU will also run fine without this output but it is just another fault code to be deleted. All inputs are through relays to the fan and the fan runs low speed using a resistor on the fan assembly.

I figure you should still be able to use all the Eurovan wiring for your AC circuit. As for your fans, if your Eurovan does not have a thermoswitch to activate the fans you will have to add one and wire it.

 

[iwannajettatdi]

Thanks for the info, Braddman. My BHW didn't have a climatronic, it was a manual control HVAC, and it has the relay 384 for the manual controls.

I've got all the wiring diagrams that were available for the B5/5.5 Passat from Erwin, and for the Eurovan for my model year (2002). And some T4 Transporter files too.

I guess my question was just, what wire needs to go into the ECU to make everything happy with the AC? From what you mentioned, I think just the after run relay signal, and otherwise the van's AC circuit and relay should work just fine? How would the ECU tell the fans to come on at low/high speed for coolant temperatures? Through the after run relay?

Again, I'm probably making this more difficult than it needs to be in my head, but I'm stuck while staring at diagrams. I'll give it another go in the AM.

Thanks again!

-Ryan

 

[PickleRick]

I installed my custom harness from faast forward automotive in my old yota. He knew I was going to run ac. He's in Canada and I'm in the deep south where we've had a day in the 80s already this month. Ac is a must. There is no provisions for ac in the harness.

I reused the ac system/wiring from the 4 runner to the bhw compressor.

I used a set of independent relays to run the electric fan. One will operate the fan when(if ever) the radiator temps hit 190.

The other will click on when the compressor sees power.

If your van didn't have ac all you'll need is to wire in a pressure switch as a fail safe. That way if the chage gets low or the freezes you won't burn the compressor. I'm using the factor 4runner (87) little computer and sensor.

 

[iwannajettatdi]

I installed my custom harness from faast forward automotive in my old yota. He knew I was going to run ac. He's in Canada and I'm in the deep south where we've had a day in the 80s already this month. Ac is a must. There is no provisions for ac in the harness.

I reused the ac system/wiring from the 4 runner to the bhw compressor.

I used a set of independent relays to run the electric fan. One will operate the fan when(if ever) the radiator temps hit 190.

The other will click on when the compressor sees power.

If your van didn't have ac all you'll need is to wire in a pressure switch as a fail safe. That way if the chage gets low or the freezes you won't burn the compressor. I'm using the factor 4runner (87) little computer and sensor.

The van came with manual control AC, just like the Passat. The relays are just numbered differently on the VW wiring diagrams because it's still using MK3 terminology vs the MK4/B5 terminology of the Passat wiring diagrams. So the van has all the pressure switches, thermal switches, coolant level and coolant temperature sensors that the Passat had, I've already got them swapped over and repinned as needed for the Passat wiring/ECU and the van to interface politely, I think.

Let me try and dig through my paperwork again, and put into writing where I'm getting stuck.

 

[oilhammer]

No BHWs had Climatronic. At least none sold here. The only B5s with that were tarted up V6 GLX models and the the W8.

The BHW's A/C system is the same as the AWM (1.8t).

You'll want to use as much of the Transporter's original A/C configuration, because that uses an entirely different system. It uses an expansion valve system (like a Golf or Jetta), not the orifice tube system like the B5 does. So I'd keep all the HVAC controls as the van had, and use nothing from the BHW controls. Only downside is, the ECU won't know the A/C is switched on for idle stabilization, but it won't matter. The BHW makes enough torque even at idle and the EDC16 system is excellent at keeping it rock steady, so it won't care if the extra load of the compressor is on or not.

 

[iwannajettatdi]

No BHWs had Climatronic. At least none sold here. The only B5s with that were tarted up V6 GLX models and the the W8.

The BHW's A/C system is the same as the AWM (1.8t).

You'll want to use as much of the Transporter's original A/C configuration, because that uses an entirely different system. It uses an expansion valve system (like a Golf or Jetta), not the orifice tube system like the B5 does. So I'd keep all the HVAC controls as the van had, and use nothing from the BHW controls. Only downside is, the ECU won't know the A/C is switched on for idle stabilization, but it won't matter. The BHW makes enough torque even at idle and the EDC16 system is excellent at keeping it rock steady, so it won't care if the extra load of the compressor is on or not.

Thanks, Oilhammer! I've been looking through the diagrams and trying to compare notes between the two systems. I just don't have as much actual knowledge of how they work in real life. After the last 2-3 hours of poking through, I had come to the same conclusion, though not as eloquently. I think my biggest confusion was with the idle boost signal, and not being able to find where it integrated into the system.

I can see on the BHW's relay 384 that there is a sw/gr wire that heads off to the ECU via pin 1/87a and through the red protective housing plug. But there doesn't seem to be a similar signal wire going to the EV ECU other than the evaporator temperature switch.

So, BHW AC relay can go, from what I'm understanding.
I'll keep the EV relay 140 for the AC system. At some point I might delve into the climatronic upgrade for the EV, but not today.
All the van resistors and fan relays are still in place. From what I've just put together, it doesn't need anything from the ECU, just the battery, coolant temperature sensors, and a signal from the AC pressure sensor.

Cool. Well, hopefully it will be.

 

[oilhammer]

Yeah, like I said, two completely different systems that work differently and share nothing. So it is best to just leave the van's stuff in place. Not sure what compressor you are using, but I would not want to use the Denso one from the BHW, I'd want to use a Sanden like the transverse stuff used (the Eurovan, regardless of engine, or any of the transverse engines in any similar year Volkswagens, the ones with a clutch). Only because I am not sure how well it would work with an expansion valve system, also not really sure how you would have mounted it in there anyway. I am picturing you having some form of hybrid BHW/BEW arrangement in there, with the compressor mounted in front, near the alternator and power steering pump.

FWIW, the B5's HVAC system is largely just a legacy arrangement from the longitudinal Audis on which it is based, from long ago. Just a simple clutch relay (they call it a retardation relay, because it also delays engagement), and the electric fan is just a relay and old fashioned resistor... there is no solid state fan control module like on transverse VAG cars of the same vintage. And the Eurovan all the way until the end mostly used the same setup it did at the start, which is a complex series of resistors and relays. But I *think* they did improve some things on the VR6 versions. My '93 T4 2.5L had a whole bank of relays up by the battery, dual fan motors with THREE speeds as well as the grill shutter deal. It was distinctly overcomplicated.

 

[PickleRick]

It would suck to find my bhw compressor didn't work with the old school system. I'm still wondering how much oil I'll be adding into the system as I'm using the old school (new replacement) dryer. You do not want to know the time it took to make a new mounting bracket that ran the belt true. I couldn't find any run-out clearances for a serpentine on the web.

20211218_133634.jpg

Higher mount bhw compressor

forums.tdiclub.com

 

[iwannajettatdi]

It would suck to find my bhw compressor didn't work with the old school system. I'm still wondering how much oil I'll be adding into the system as I'm using the old school (new replacement) dryer. You do not want to know the time it took to make a new mounting bracket that ran the belt true. I couldn't find any run-out clearances for a serpentine on the web.

20211218_133634.jpg

Higher mount bhw compressor

forums.tdiclub.com

I feel that. I'm still a little worried about munching a belt. I think everything is lined up, but we shall see. I probably had 60-100 miles on it as it is now and it was ok. Time will tell. I'm using the Eurovan compressor and either an ALH or BEW accessory bracket, so... fingers crossed. I did have to swap alternator pulleys.

Yeah, like I said, two completely different systems that work differently and share nothing. So it is best to just leave the van's stuff in place. Not sure what compressor you are using, but I would not want to use the Denso one from the BHW, I'd want to use a Sanden like the transverse stuff used (the Eurovan, regardless of engine, or any of the transverse engines in any similar year Volkswagens, the ones with a clutch). Only because I am not sure how well it would work with an expansion valve system, also not really sure how you would have mounted it in there anyway. I am picturing you having some form of hybrid BHW/BEW arrangement in there, with the compressor mounted in front, near the alternator and power steering pump.

FWIW, the B5's HVAC system is largely just a legacy arrangement from the longitudinal Audis on which it is based, from long ago. Just a simple clutch relay (they call it a retardation relay, because it also delays engagement), and the electric fan is just a relay and old fashioned resistor... there is no solid state fan control module like on transverse VAG cars of the same vintage. And the Eurovan all the way until the end mostly used the same setup it did at the start, which is a complex series of resistors and relays. But I *think* they did improve some things on the VR6 versions. My '93 T4 2.5L had a whole bank of relays up by the battery, dual fan motors with THREE speeds as well as the grill shutter deal. It was distinctly overcomplicated.

Thankfully, there isnt quite the mess that that sounds like. There is a fan control module that mounts just behind the left headlight, and a few resistor packs down by the fans. All of that is still the van wiring and untouched. I was able to use the van's ground to the starter, but I remade the positive lead when I was crimping my winch leads. The Passat alternator cable works just about perfect.

Last thing to button up there will be the outside air temp sensor. It's in the same multiplug as the Passat's air con pressure plug, AC trigger wire, and something else. It's all depinned, I'm just trying to find a donor plug to swap so it's a little cleaner.

Thanks for the help!

 

[Zeitgeist]

The ALH in my Vanagon uses it's original Mk4 compressor along with all the factory Vanagon A/C stuff, just fine. No problems at all. I don't think my '01 EV or '04 Passat have too much A/C design difference than the '01 Jetta donor for my Vanagon.

 

[oilhammer]

They do, actually. Once again, the B5s use an orifice tube system, not expansion valve. The Vanagon's kluged-on A/C system is expansion valve. The Eurovan is expansion valve (if it has rear A/C, it has TWO of them). ALH cars, expansion valve. And all these expansion valve Volkswagens use a Sanden compressor, although the Vanagon got a generic fixed type cycling setup, whereas the Eurovans and ALH cars got a more modern non-cycling variable displacement type. The B5 uses a smaller displacement Denso compressor. The B5's A/C system has as much in common with the others as the A/C system from a Chevy van.

 

[PickleRick]

So does the passat compressor not put out the proper pressure or is it not heavy duty enough to do the job? Inquiring minds want to know why it won't work...on say an old expansion valve system.

 

[oilhammer]

I honestly don't know if it would work, or would not work, or would be compromised for longevity, or what. I'm merely stating it is not the same, and it probably is not calibrated the same. I know it is physically smaller, and I am pretty sure it has a smaller displacement (maximum). They also hold less refrigerant (600 grams vs. 750 grams for the transverse cars with expansion valve systems).

I think of it all as a "system", and it is all designed to work in concert with one another.

Expansion valve systems use a desiccant in a drier on the high side, of a small volume, next to the condenser. Orifice tube systems use a giant accumulator that has the desiccant, on the low side, BEFORE the compressor. This prevents compressors from pulling in a liquid and blowing up. It would stand to reason that the Denso compressor's inlet port, and its maximum displacement, is calibrated so that it has no worries of this happening with the accumulator to protect it. The Sanden compressors on the expansion valve systems pull the refrigerant in straight from the evaporator.

 

[PickleRick]

Thanks for the explanation. I may try running the red tek 12a (not the illegal 12 for you tree huggers who shouldn't be on a diesel forum anyway). It's 12 and r134 compatable, more efficient than r134 and most importantly runs at lower pressure than r134 so that may help with the expansion system issue on the denso pump.

My excursion has not one but 2 expansion valves and she sucks with r134a at idle but will have you frozen on the freeway. The passat, as all of you know, could keep frosty alive all summer on full blast in bumper to bumper traffic.

 

[oilhammer]

Refrigerant compatibility is less of a concern as the lubricant compatibility. I'm always left scratching my head as to why anyone messes with changing it anyway. But if it is all flushed out, then it shouldn't matter. R134a is cheap, widely available, and works perfectly fine, anything else seems to be a solution in search of a problem. Maybe in 10 years we'll be dealing with a change to R1234yf, though, who knows.

 

[PickleRick]

If you ever have a customer with an old r12 systems compain it's just not cold enough give red tec a try. It lubes better than r134a...which isn't hard to do. R12 is more effective than r134a. R12a isn't as efficient as r12 but it's superior cooling properties to r134a so you don't have as much cooling loss at idle or bumper to bumper traffic speeds

I suspect st Louis doesn't have near as long or extreme of summers as we have down here in our nation's arm pit.

The bhw compressor interchanges with many vw audi models, back to the early/mid 90s so I suspect it was used with r12 way back then. I cannot remember when the switch was. It was still orifice tube back then.

 

[oilhammer]

We haven't had an R12 car in here in quite a while. Any of mine were converted long ago. My '91 Jetta ran longer on R134a than it ever did on R12, as I think I converted in some time in the late '90s. Every manufacturer had conversion instructions, and often parts or kits, it was just that not everyone bothered to do them correctly. I probably did 1000+ conversions, maybe more.

We get triple digit temps here, and high humidity. Summers suck here.

R134a came about first in 1991 in the new-for-that-year MB S-class. Then in 1993 VAG products got the switch, except the Cabriolet as that was its last year and I guess they figured it wasn't worth the effort. 1994 for most everyone else except some Jeep Cherokees, which got it for 1995.

 

[turbocharged798]

12a is a hydrocarbon refrigerant that is extremely flammable. No way I would ever put it in my car.

 

[PickleRick]

Gasoline is even more flammable/explosive yet its pretty popular among the auto and marine world.

HC is basically propane, yes a popular alternative fuel, but it makes up only a small percentage of r12a. The oil in the system is more flammable than the r12a.