I've been driving the car for years w/o any of the climate controls working and figured I'd try to troubleshoot if finally. I know I'm probably opening a can of worms here. The defogger button works which is the way I heat the car in the winter. But nothing happens when I touch any of the other buttons. Where should I look first? What should I try testing to see what needs to be replaced. I have the automatic climate control. This system seems very complex?

The system you have is called Type II climate control, which was used up to model year 1980, and yes it is complex -- a system licensed from Chrysler, which used it in their old Imperial models.

When it runs in defrost only, that is what I would roughly term a 'fail-safe' mode. It means that some component of the system is defective so the system cannot work as it ought -- but defrost works separately as a safety measure. Unfortunately, with defrost you get maximum heat.

Here is a link to the Chrysler manual that describes how the system works. You need to read this and understand it before you begin to poke around:

1971 Chrysler Imperial Auto-Temp 2 Service Reference Guide - Session 281

The most common failure item is the SERVO under the hood, the big black thing with the hoses and wires running into/through it that you see to the left of the motor. Unfortunately that is also the most expensive part of the system, and I do mean expensive. So you need to work it through step by step and not just go to the usual suspect, as failure of other components will also cause the same symptom.

After you understand how the system works, you can go here:
http://www.startekinfo.com/StarTek/outside/12265/disc_2/program/climate_77_3d.htm

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

If you do replace the servo be sure to replace the climate control amp as well, a bad amo can take out a good servo. If the car is especially nice and you plan on keeping it indefinitely there is a digital upgrade kit that replaces the servo. Before any of this however you need to determine if the servo is still working or if the issue is simply a vacuum leak somewhere.

__________________
2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

Thank you...I'll begin reading up on it. I didn't know if there were some preliminary spots to test with a test light to see whats going on? I just started to check through the STAR tek info link you gave me and when you click on something it reports a bad link?

So I see when I try it myself. I sent you a message with a suggestion.

It would be worthwhile to buy the factory manual. They are available on eBay (on CD). That's what you were looking at online (well an index page anyway).

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I own the 1980 and replaced the servo with an aluminum body and did replace the amp.

After that:

Check the quality of the vacuum line harness that runs from the servo on
the passenger side fender well to behind the battery.

Could be really brittle, but look for broken or split lines.
I replaced my broken pieces with standard white line being careful to
watch the color I was replacing.
This entire vacuum harness can be had at junkyards and from suppliers.

The harness goes under the glovebox (behind the glovebox is that crucial amp).
Remove the panel under the passenger side glove box to inspect the vacuum harness that comes from the servo under hood.

Now, one vacuum line comes from the drivers side cabin wall. This brings in crucial vacuum that runs to the button panel. I found this one line, green I think, to be really important. Under the hood this one green line basically goes to the main vacuum pump line and supplies vacuum.

Of course, after all that visual inspection if the pods leak that open and close vents you will have other troubles. But these tips above and that excellent diagram listed will start you on your path.

I pondered replacing the servo with the digital replacement but have concluded my servo actually does a good job. My issues are with my button panel. I replaced it with one that passed a vacuum test and am pleased.

For me, the next step is a simple fan switch override that will have manual control for fan speed, Off 1 2 3 4 - then I will add a AC compressor override
switch. That will handle cooling as long as the button panel can handle the vents.

Next , if that works, I will add an electric valve for the hot water in winter time to control hot water flow.

All these override systems will be in conjunction with or parallel to the factory system, and wiring. Because sometime the factory system kicks in.

I would rather have a perfect factory system. But after owning this 28 years,
have just gotten to tired of it to worry anymore and will simply purchase a 1982 or newer.

I have had my interior system stripped up to the firewall and never could find a decent way to re-engineer this.


Keep us posted on your progress. As a 1980 owner I am always interested in
what others learn.

Good Luck!

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

Well honestly this is WAY too much to get into. This is an extra fun car to have that's basically free to drive (wvo converted w/diesel blend) I just wanted to finally fix the HVAC system, but its too complicated and I don't need it that bad. I drive my 2000 SL500 as my primary car so I'll just use the defroster to heat the w123 in the winter when I take her out. Thanks for all the info though.