300D AC Charging - Help! - Page 2 - PeachParts Mercedes-Benz Forum

tangofox007 · #16 06-01-2006, 10:30 PM

Quote:

Originally Posted by tobybul

I thought thats just for testing the system and not nedcessary the low side fitting.

When working on air conditioning systems, thinking that you know what you are doing isn't good enough.

Motorhead · #17 06-01-2006, 10:51 PM

Quote:

Originally Posted by tangofox007

Which is an excellent location for a high side valve. No telling how many lives it has saved, being located in an out-of-the-way place.

Well if you are a moron trying to do something that you have NO business doing...... Then it IS in a good place.

From a mechanics point of view, someone that KNOWS what they are doing, It is in a stupid place. In all other A/C systems that I have worked on, I have never seen the high side port under the car.

Matt L · #18 06-01-2006, 11:04 PM

Quote:

Originally Posted by Motorhead

Well if you are a moron trying to do something that you have NO business doing...... Then it IS in a good place.

From a mechanics point of view, someone that KNOWS what they are doing, It is in a stupid place. In all other A/C systems that I have worked on, I have never seen the high side port under the car.

Any AC technician worth his pay could trace the high-pressure lines and find it in less than a minute. I did that and I don't get paid for AC work. It's in a great place, especially considering that the high-side and low-side fittings are identical, other than the size of the line to which the fitting attaches. A less knowledgable owner may not notice the difference, were they both easily accessable.

Now, they really did hide it on the 210. Of course, the AC diagnostic manual shows its location.

mobetta · #19 06-01-2006, 11:19 PM

Quote:

Originally Posted by tobybul

1985 300D. I already put a belt on. Clutch is not siezed. Spins well and now with belt on turns good and no noise. I suspect system has very low charge per my comment above. Thats why not kicking in. Pressure switch not sensing pressure.

Where are the low & high side fittings??

if you jump the pressure switch wires(on the receiver/dryer) you will get the comp. to engage, then see how it sounds. dont do it for too long, though.

i just got a freeze 12 kit from ebay ($50,shipped) and was wondering about topping off r 12 w/ it or should i just evac. the system, replace the dryer,valve,etc first.

already spent $600 on her this week, so if it is the long road, it will be a while.

Matt L · #20 06-01-2006, 11:53 PM

Quote:

Originally Posted by mobetta

if you jump the pressure switch wires(on the receiver/dryer) you will get the comp. to engage, then see how it sounds. dont do it for too long, though.

i just got a freeze 12 kit from ebay ($50,shipped) and was wondering about topping off r 12 w/ it or should i just evac. the system, replace the dryer,valve,etc first.

already spent $600 on her this week, so if it is the long road, it will be a while.

The advantage to having it evacuated is that the refridgerant can be easily recycled, and it's worth money to the recycler. As soon as you add anything else to it, it costs money to destroy it, and most shops won't touch it.

If the current dryer is compatible with the refridgerant that you're using, you probably only need to evacuate it to a deep vacuum for a half-hour or more immediately before you add refridgerant (this is assuming that the original charge was reclaimed earlier or at that time). But this is unlikely to be the case.

Note that it's not legal to fit many refridgerants directly after R12. If you first convert to 134a, you can again convert to more types. As I said earlier in this thread, if you can just stay with R12, you should.

NOTE: your instructions to jump the low-pressure switch are inadequate. If there is ANY refridgerant left in the system, once you jump the switch, the compressor will not stop when you remove the jumper. This is because the low-pressure switch is on the high-side line, and it's not a cycling switch. To stop the compressor once you jump the switch requires turning it off at the climate-control panel, or shutting off the engine.

mobetta · #21 06-02-2006, 12:07 AM

thanks for the tips- the switch thing makes since. I was just referring back to a ford ranger that i had- that was in the haynes manualfor charging the system.
I will find a shop to reclaim my r 12.

tobybul · #22 06-02-2006, 08:11 AM

Thanks for all the feedback.... but it doesn't sound like anyone has really done this before, ey? I just ordered a dvd from Ebay that supposedly will tell everything I need to know.

Y'all have a point about maintaining the R12. I will first try to do that. Right now, I have the R134A conv kit sitting on the side ready to use.

Hit Man X · #23 06-02-2006, 08:26 AM

Quote:

Originally Posted by tobybul

Thanks for all the feedback.... but it doesn't sound like anyone has really done this before, ey? I just ordered a dvd from Ebay that supposedly will tell everything I need to know.

Y'all have a point about maintaining the R12. I will first try to do that. Right now, I have the R134A conv kit sitting on the side ready to use.

Doesn't mean you have to use the 134A...

tangofox007 · #24 06-02-2006, 10:11 AM

Quote:

Originally Posted by Matt L

NOTE: your instructions to jump the low-pressure switch are inadequate. If there is ANY refridgerant left in the system, once you jump the switch, the compressor will not stop when you remove the jumper. This is because the low-pressure switch is on the high-side line, and it's not a cycling switch. To stop the compressor once you jump the switch requires turning it off at the climate-control panel, or shutting off the engine.

Are you certain about that?

According to the "Compressor Clutch Control" electrical schematic, the compressor clutch is powered directly through the low pressure cut-out switch. Breaking that connection should cause the clutch to disengage.

tangofox007 · #25 06-02-2006, 10:14 AM

Quote:

Originally Posted by tobybul

Thanks for all the feedback.... but it doesn't sound like anyone has really done this before, ey?

Not sure what you mean by "this." But if you are talking about a conversion to R-134a, I have done it. And I have been sorry ever since. Next week I am going to "convert" back to R-12.
'82 300D.

tobybul · #26 06-02-2006, 10:24 AM

I was referring to not being able to tell me where exactly the fittings are/is to fill the system and any other details or steps involved in the process, whether R12 or R134.

tangofox007 · #27 06-02-2006, 10:33 AM

The low side valve is in the suction line that crossses in front of the engine just behind the radiator. The high side valve is in the vertical hard pipe on the right side of the engine. If you follow the large hose from the condenser toward the compressor, you will find it. Just above the lower oil pan.

Matt L · #28 06-02-2006, 10:34 AM

Quote:

Originally Posted by tangofox007

Are you certain about that?

According to the "Compressor Clutch Control" electrical schematic, the compressor clutch is powered directly through the low pressure cut-out switch. Breaking that connection should cause the clutch to disengage.

Ah yes, that it will. I was referring to jumpering the connections with the switch still in the circuit.