Air Conditioner Tuning

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....back in the saddle again....
Sep 29, 2004
Truckee, CA
As the temps rise around here, I'm looking for ways to help the truck stay cooler.

Already have tint installed.
Trying to use the window-reflector stuff more often.
Adding some insulation to firewall and tranny hump.

But I'd like to look for ways to get my A/C to work even better.
I had it recharged about six months ago- it still blows almost as cold while driving, but at idle or low-rpm it doesn't put out much. I'll get it leak-checked soon (the equipment is 4 hours away) and see if it has lost refrigerant.
But I'm wondering: is there something I can do to:
increase the fan efficiency?
get more cooling at lower rpms?
just basically make the system run better?

Thanks in advance!
With A/C temp and pressure are realitive. The higher the temp the higher the pressure. At idle, less air across the condensor will rise the pressure and less COOL air. It could eaisly be solved with an aux fan. Plus the fan could lend itself to the the overall cooling in summer traffic or heavy loads. General rule is everyone tends to think it is a leak or low on charge. More often then not it is related to air flow and not refrigerant. Also, do you still have R-12? That stuff is worth more then "well just about anything". I would hope you dont need to top it off.

Good sorce for an aux fan is ebay. Search E28. You will get lots of pages of BMW parts. The fan assembly is narrow, wide in diameter and constructed very well. Plus they are very affordable. Lots of guys parting the east coast rusted ones out. I just sold a 84 533I and gave my spare parts away. I wish I still had my fan because I see potential on my new 85 60 for it.

I'll look into it.
I think the first step is to spend some quality time straightening the condenser fins-- lots of them look like they got hit by a powerwasher and are sorta flattened out. I imagine that makes a pretty big difference.

The odd thing is that the motor tends to run cool... but certainly when it does heat up, I also get much worse A/C performance.

What would be the minimum-sized fan to get results?
A fine tooth comb works very well to assit in strighting the fins. make sure the condensor is clean. the more air across the condensor equals more heat out of the refrigerant equals colder temps in the cab. Good Luck. I am a 60 rookie but I have repaired many commercial A/C units.

I like the comb idea! I happen to have a hotel comb handy that I can probably cut down to a narrower size, easier to use. Thanks!

I plan to install some window screen on the backside of the plastic grill as well-- that really helps keep the bugs out of the condensor and I suspect it might help reduce the power-washer damage too (car cleaners here LOVE power washing the exterior)

You might check for obstruction in the condenser itself. These can usually be identified - run you hand over the surface of the condenser with the air on and the engine idling. You are looking of variations in temperature that indicate unequal circulation.

If your condenser is the problem, I have a really clean spare that might help you out.

Steve, my bet it that the recharge guy did NOT properly recharge the system. When I had my frame swap done in Tegucigalpa the local guy there only evacuated it with an old compressor and that is NOT sufficient (I know most Central American guys only use that but you NEED someone with a vacuum pump to do it right). Make sure the guy draws it down to 30" and then make sure it can hold 30" with the vacuum pump off for a 1/2 hour or so. My A/C worked like crap when evacuated with the compressor in Tegus but was just fine when a guy in Guatemala did it with a vacuum pump (it cost more to get done right but it's worth it). It kept the truck cool with 7 of us in Tikal over the Christmas holidays.
ahhhh, Tikal. One of the best places in the world.

The A/C worked too cold at first, then it settled down to good. But that was with cooler weather, wetter air, and on the road. Now with much hotter, drier air and slower speed driving, it isn't quite up to the task.

I've looked at the condensor, and it definately needs a little help on the fins. But I can believe the recharge thing as well... next time I'm in SJ, I'll look into it, along with a die leak-test.
sandcruiser said:
ahhhh, Tikal. One of the best places in the world.

Even better is the area behind Tikal, Uaxactun and that on up to the Mexican border. Remote, not often visited and good for backroads exploring since no one else visits those ruins.
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Sandcruiser - little off topic here, but how far are you from La Roca Bruja, or Playa Langosta?

Just dreaming of warm water...sorry my wetsuit is still cold and wet

Pleasure Point, CA
I used to live about a 1 minute walk to Playa Langosta ("Langy"). Surfed there this morning. Infrequent sets, but about chest high and decent shape. Take a look at for a photo from Langy about a week or two ago.

Witches' Rock (Roca Bruja) is about 2 hours away. Much longer if you drive. But I think we are headed there in March to camp a night or two (in the cruiser, of course) and surf. Some buddies took a 40 ft Cat out there last weekend... took them five or six hours to sail up, but they got some really great surf and also hit up Ollie's Point, which is my favorite wave anywhere- near-perfect shape, ultra-predictable point break. Loooooong right.

You have ruined my day.

Anytime you need help wrenching on your rig let me know! I could always tell my wife it was a "business trip", though she might get wise when my 9'6" noserider isn't in my quiver anymore....

Long rights...mmmmm..better than beer


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