My there's alot of A/C posts in the middle of the summer...

I got a junkyard Volvo compressor fan and wired it with relay, tripped by the compressor clutch wire. I had never payed much attention before, but the compressor really doesn't run much. Even turned up 3/4, it's maybe 25% duty cycle. Do I need to trip the fan relay from some other source so it run's more often? If I understand A/C system, there is flow through the condensor wheather or not the compressor is pressurizing.

The second question is the fan is loud, and makes the whole car vibrate (the steering wheel rattles even). Do I need to balance the fan or isoloate it somehow? It is a stock Bosch fan, I disassembled, cleaned and lubed bearings.

Thanks,
Peter P.
Portland, OR

Hey Peter...

I'm in the process of doing a similar job on my '80 245, and I might stop by to check out your set up if I see you out working on it, that is if you don't mind.

Where did you get your fan from?
--
If you listen to the radio in Portland, OR, you may know me as 'Portland's Favorite Soul Brother!'

I learned something new today. The compressor cycles alot less often in the cool of a late night. This afternoon with temp's at least 100 and the interior fan and knob turned most of the way up the compressor was almost continuously on in traffic. The alternator and motor where working hard. But the A/C was frigid!

So wiring the aux. electric pusher fan to the compressor clutch is just the ticket. It only runs when the system is in dire circumstances. I imagine on the highway there is alot less running.

HearToTempYou,
Stop on by whenever, I'm on 53rd, white '88 245. Although for the fan install I was working at night, up to almost 1am. I hope my neighbors forgive me, but it's the only free time I can make for myself.

Peter P.
Portland, OR

"Although for the fan install I was working at night, up to almost 1am. I hope my neighbors forgive me, but it's the only free time I can make for myself."

You wouldn't believe how many times I've stayed up past 1:00am trying to finish up some task on my Wagon... Last time I was up late was when I was replacing the Rotors on my wagon for the first time...

I think I know your car... (I have a buddy that lives on 54th, but I drive down 53rd a lot so I can park in front of his place which is near the corner of 54th and Fremont). It's the Wagon with the 780 wheels and the 3rd back seat, correct?

If you're ever in need of someone to help you with the car during the later hours, just send me an email. There's a good chance I'm up anyway, and I need to start learning about these newer 240s... (Soon the family is going to pick up a late model 240 to replace either my mom's '01 camry or the '77 244... I sure hope it's the camry... heh heh heh...)

I'll stop by if I see you out, although I don't plan on doing too much driving with this hot weather we are having lately... You'll know it's me. I'll be driving something from my fleet:



(Probably not the '76 though... it doesn't quite run... yet...)
--
If you listen to the radio in Portland, OR, you may know me as 'Portland's Favorite Soul Brother!'

If the compressor cycles on/off quickly, as in every 2-3 seconds, then that's an indication of a low charge. If the cycles last a while, like 20 or more seconds, then that would be an indication of a healthy charge.

Yes you are correct, even thought the compressor is not running there is still high pressure (heat) in the condensor which flows through the TXV under your dash. Hence, in my opinion, it is a good idea to have the fan running all the time when the A/C is turned on. No recommendations on how to wire this.

For the viration, I would look at the stability of the mounting, and where you mightr have mounted it.... BTW assuming this is a pusher fan and it is mounted right in front of the condesnor (behind the grill). Stock fan still there.

Good luck!
Greg Mustang
Montreal - Ottawa
Canada