A/C questions

Andre, I pulled the fan on a friends 2800 and it was stuck pretty well, I took it apart and flushed it out with starting fluid and lots of compressed air. I was in a hurry to get it back to the paint shop (third time) and forgot to test it but I would start with a thorough cleaning.
 
Sounds like its not some electrical connection issue that I may have missed and taking the unit out is the suggestion.
 
The vent fan is not an issue, the one in the engine bay by the windshield.

The auxiliary fan, in front of the condenser and the radiator is also working.

Its the AC fan that is not working, the 'squirrel gage' fans right behind the center console on top of the evaporator.

Looks I'll be taking out that fan. As per the blue book, I started by taking out the 2 bolts that holds the center vent and tried to pull out the vent unit. Can't do it, something is holding it in besides those two bolts. The picture in the blue book on how to remove the evaporator is not what I have. In the pictures there a cig. lighter and another switch. I have the vent levers there.

Do I have to disconnect the lever cables just to get the vent out enough so the evaporator can come out?
 
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The lever panel will swing out of the way (2 screws each side into the underside of dash tray?) without disconnecting the cables.

I think you 'll need to remove right side console panel to make things easier. Isn 't the fan housing part of the evaporator housing? Or are they separate? (I don't have my photos on hand to reference). If the same then you would need to remove the glove box and disconnect the AC lines at the firewall.
 
Thanks for your and help and suggestions Steve.

Your first link will not work. It would be impossible to remove the fan motor without taking out the evaporator. You have to separate the two halves of the evaporator sufficiently to take out the motor and it can't be done.

Your second link shows the procedures in the blue book. They make it look easy but its not. The pictures shown are not from an e9. Maybe an e3 or some othe European model. I've never seen a vent unit with a cig. lighter and other switch. I have all the levers, vents, defrost etc, in that section. This means that to remove the vent section I have to indeed disconnect the vent cables.

This would be OK but what I see as problematic is unscrewing the two pipes leading into the evaporator. I had to buy wrenches since I didn't have a 24 mm and a 30mm to disconnect the larger pipe. I'll try tomorrow and keep you posted. They look very hard to disconnect with the 'anti condensation tape' around it that I had to scrape off.

Once in awhile I see an evaporator for sale and I wonder how did they disconnect the two pipes or did they simply cut them off.
 
Finally, got the evaporator unit out. Now to test the fan motor which was giving me the problem.

This is not a task I would want to do again. It'll probably be harder to put back in.

I'm surprised that no one has ever posted procedures to take out the evaporator on this forum. I searched but couldn't find anything.

If someone did, then maybe a link could be posted in a new thread.

When I'm done I will give it a shot.
 
update on A/C questions

OK. Managed to take out the evaporator unit and put it back in.

This was an incredibly difficult task. In comparison, taking out the dash and reinstalling it is a piece of cake in my opinion.

Anyway, the 'squirrel' fans were not turning because of dirt/dust accumulated over 42 years. After using Power Blaster and then oil they finally moved freely.

Before taking out the evaporator box I had filled the system (so I thought) with R12. When I then turned the AC on, the compressor clutch would engage but felt no cold air coming out. The fans were working briefly and then became stuck which prompted me to take out the evaporator.

When I took it out and disconnect the two pipes leading into it nothing came out of the pipes. I had thought whatever amount of R12 I had put in would escape then but there was nothing.

When I reinstalled the evaporator and reconnected everything, all flaps would open close correctly and the fan also operated correctly.

However, the compressor clutch does not engage. Is this because the system is empty or did I screw up the compressor by turning it on for a short time while on 'empty'

Any thoughts/ suggestions?
 
Yes, removing the evaporator assembly is an incredible pain in the butt. I've had mine in and out several times after I retrofitted a/c into the car at least 15 years ago, and each time, I think that plastic piece that mates the top of the evaporator to the rest of the air flow system is going to shatter into a million pieces.

You say "When I took it out and disconnect the two pipes leading into it nothing came out of the pipes. I had thought whatever amount of R12 I had put in would escape then but there was nothing." Just so we're all on the right side of the law and we all have a clean environmental conscience, what you really should've done was a) hooked up a gauge set to the car with everything off and seen if you had any resting pressure in the system, indicating the presence of gas (R12), and if you did, b) taken it to an a/c shop for them to recover it. But, yes, if you disconnect the pipes (or depress the charging valves) and nothing comes out, there's nothing in there.

You say "However, the compressor clutch does not engage. Is this because the system is empty or did I screw up the compressor by turning it on for a short time while on 'empty'?" Most systems are installed with a low-pressure cut-off switch that prevents the compressor from engaging if the system is empty. When recharging, you either need to recharge slowly so R12 wafts into the system until there's enough pressure for the low pressure cut-off switch to see, or bypass the cut-off switch.

But... before you do anything, since you've had your system apart, I strongly recommend you leak-test it. The single longest chapter in my book is on air conditioning, but basically you need a gauge set, a tank of nitrogen, and adapters to hook them together. You first pump the system with 50 psi of nitrogen and listen for big leaks. If you don't hear then and if the gauges sit at 50 psi, then pump it up to, oh, 100 to 150 psi. Best to let it sit overnight. If it's still at 150 psi in the morning (may be slightly lower if the garage cools at night), then you're good, but if it's down, you've got a leak and you need to find out where it is. If it's in the evaporator you've just installed, you get drunk, cry, and get drunk some more (been there done that).

You really need to do this before you recharge with R12. Once it is leak-free, you evacuate it (pull a deep vacuum for at least 45 minutes to boil off any moisture), then recharge.

Or take it somewhere and pay them to do it. No shame in that. I did it for years (replaced parts but paid someone else to leak-test and evacuate) before I began doing it myself.

--Rob
 
I dont think these old systems have a low (or high) pressure cut off. Are you getting 12 volts to the compressor clutch when the switch is on?
 
The a/c in my 81 E24 was not factory installed, but,rather, dealer installed. There were some various swathes sent to the dealers in the kit for an install at the dealer ship. My car is a euro and it could have been installed here or there. However, on my receiver drier there was a low pressure switch. All of the receiver driers I have seen new, have a provision to put a switch in.
 
Question: might belong in "off-topic" but I'm wondering about this R12 thing: don't get me wrong, I would not recharge/discharge my A/C by myself- It's not that I feel I couldn't learn, but have no interest- for me it belongs in the realm of bending pipe for exhaust systems- take it to the shop and let the pros do it. I digress.. What exactly is the problem with R12? I like to think that I am an environmentally conscious person, recycle, re- purpose, really- I try. I recycle all my fluids yada yada, what is it about R12 that is worse than say the chlorine that we put in our pools, or is it just that the government says it's bad? That would be the same government that puts flouride in our water to keep our teeth white, uh riiight. OK, but I am asking seriously.
 
Steve,

I think you're right. No power to the compressor. When I connect the compressor to a power source I can see the clutch engaging in and out. Have to follow that wire and see if there is a broken link somewhere. The aux fan is also no working not sure if the two issues are connected. The aux fan did work before I took out the evaporator unit.
 
update on A/C questions

OK. I believe I’ve isolated the problem.

Here is a recap so you don’t have to re-read the entire thread.

I have factory installed AC. The AC system was not turned on for about 10 years. When I turned it on, with engine running or just with ignition on, the AC clutch would engage, the auxiliary fan would turn and the AC fan (squirrel cage) would operate.

I performed a vacuum, it held steady, filled the system (so I thought) with 2 cans of R12 with engine running and AC at full blast. Then noticed the AC Fan (squirrel fans) would get stuck.

Removed the evaporator, clean up the AC fan and re-installed the evaporator.

Turned on the AC, AC fan now spins freely but compressor clutch would not engage and auxiliary fan would not turn.

Double checked all connections, followed the wiring diagrams in Blue book, section 64 in Blue book. Checked with testing light, voltmeter and everything seemed to wired correctly.

Tried 3 different relays (below coil) and still it would not work except for the AC fan.
Opened one of the relays and when I pressed on the plate inside, the clutch would engage and the auxiliary fan would work.

Checked all wires, connections etc again and everything seemed fine.

I tried 3 different AC thermostat switch and still nothing. I then disconnected the 2 wires on the thermostat switch and replaced it (for testing) with a simple on/off switch.

When I turned this switch on, the relay below coil would work, clutch would engage, auxiliary fan would work and the AC fan works. This, whether the engine is on or simply with the ignition on. I opened one of the thermostat switches to look at the innards. There is a small diaphragm that expands and contracts which provides contact to a plate and sends a signal to the relay to turn on. It seems this diaphragm is not working.

What I find strange, though not impossible is that 3 AC thermostat switches would be defective, Two of them have the thermostat ‘wire’ broken off but that should not affect the on/off function.

It looks like I need a new thermostat switch. One more thing, the ‘flying fuse’ as called by the blue book coming from the auxiliary fan has continuous power whether the ignition is on or off.

Any thoughts? Have I missed anything or other tests I could perform?
 
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