I am working on an 85 300d for a friend (oil/filter/fuel filters/etc). He told me the a/c was working great, then quit one day.
I checked the fuse panel and found the fuse for the blower had blown. I replaced it with a new fuse (25a - blue) and the blower works now, but the compressor does not engage.
Are there any other fuses/relays that I need to check?
I've searched this forum, but could not find any answers.
Thanks.......Dennis

__________________

all TURBODIESEL fleet:

"aRBee" 1985 300D anthracite grey/palomino
"the Corporate Jet" 1997 Volkswagen Jetta TDI (Sandy's car)
"Sherlock"- 1982 MB 300CD white/palomino (Kellee's car)
"Betty" 1981 300D light ivory/palomino (Kristy's car)
"Harrison II"- 1997 Ford F250 Crewcab white/grey - 7.3 PSD running a WVO/RUG blend in 2nd tank.

I'd be happy to help, but there's got to be about a half dozen recent threads about A/C and compressors. Scan those and you'll find some possible causes.

More specificity is better when asking for help. What fuse did you replace? #8, or the external fuse holder, if any?

Have you looked at the wiring diagram? Or the fuse diagram? Do you have a voltmeter?

How long ago did it quit?

R12 or 134a isn't necessarily relevant to the compressor not engaging right away, but it may be relevant to whether the system has a charge and how you check it.

Just replaced #8 fuse.

__________________

all TURBODIESEL fleet:

"aRBee" 1985 300D anthracite grey/palomino
"the Corporate Jet" 1997 Volkswagen Jetta TDI (Sandy's car)
"Sherlock"- 1982 MB 300CD white/palomino (Kellee's car)
"Betty" 1981 300D light ivory/palomino (Kristy's car)
"Harrison II"- 1997 Ford F250 Crewcab white/grey - 7.3 PSD running a WVO/RUG blend in 2nd tank.

I, too, am troubleshooting an 85 300D A/C challenge...here are some places to start that I'm currently going through...

Low Charge switch (on receiver) keeps compressor from engaging due to low freon - easy check with meter for electric side, check pressure in system for appropriate charge.

Evaporator switch kicks compressor off if evaporator temp <32* to prevent icing of evaporator - easy check w/meter

Throttle position microswitch on valve cover - easy check w/meter

KLIMA relay located just in front of fuse box / brake booster under a plastic cover, digests info from kickdown, throttle, pushbutton unit, low charge & evaporator temp switches to determine whether to engage clutch on compressor - wish it was easy to verify working order, I havent been able to find a good wiring diagram or test procedure specifically geared to 1985 300D / KLIMA # 001 545 74 05

Push Button Unit - poor/broken internal solder connection(s)

Climate control unit (solid state unit behind glove box) poor/broken internal solder connection(s)

Most all of these have extensive threads in the forums, that said I'm still diagnosing min. When/if I figure it out I'll post the results.

I'm all ears for where else to look, forum guru's...

300dOwner,
Thanks for your reply. My brother will bring some tools (meter,etc) tomorrow to help me diagnose the problem. I will go down the list you provided and I am confident we can find the answer.
Like I always say, "if you put 1-1/2 heads together, you can usually come up with the right answer".
One guess who is the 1/2 head this time.......Dennis

__________________

all TURBODIESEL fleet:

"aRBee" 1985 300D anthracite grey/palomino
"the Corporate Jet" 1997 Volkswagen Jetta TDI (Sandy's car)
"Sherlock"- 1982 MB 300CD white/palomino (Kellee's car)
"Betty" 1981 300D light ivory/palomino (Kristy's car)
"Harrison II"- 1997 Ford F250 Crewcab white/grey - 7.3 PSD running a WVO/RUG blend in 2nd tank.

About $700 later, the A/C blows 32 degrees at the vent - bbrrrrrrrrrr
Thanks for the help.......Dennis

__________________

all TURBODIESEL fleet:

"aRBee" 1985 300D anthracite grey/palomino
"the Corporate Jet" 1997 Volkswagen Jetta TDI (Sandy's car)
"Sherlock"- 1982 MB 300CD white/palomino (Kellee's car)
"Betty" 1981 300D light ivory/palomino (Kristy's car)
"Harrison II"- 1997 Ford F250 Crewcab white/grey - 7.3 PSD running a WVO/RUG blend in 2nd tank.