Not getting desired vent temps after Sanden conversion - Page 2 - PeachParts Mercedes-Benz Forum

funola · #16 06-04-2014, 11:53 AM

Quote:

Originally Posted by jcyuhn

Have you made the modification for 100% recirculated air? A standard 123 mixes in 20% outside air even when in recirculate mode. Given the humidity in DFW lately (temp: low 90s, dew point: 72) your discharge temps will be quite adversely impacted by all the moisture which must be condensed out of this air.

I found the a/c in my '84 300D inadequate around town and marginal on the highway in Dallas. Modifying the fresh air door to close when in recirculate mode was good for a ~5 degree drop at the vents on a hot, humid summer day. Somewhere way back in the archives (or on the old Mercedes mailing list run out of Austin - anyone remember that?) is a write up of the process.

I'd like to see the write-up for the 100% recirc. air mod if you can find it.

remotemark · #17 06-04-2014, 11:58 AM

As the 123 doesn't have a recirc button, how do you know when it goes into recirc?

jcyuhn · #18 06-04-2014, 12:22 PM

Quote:

Originally Posted by funola

I'd like to see the write-up for the 100% recirc. air mod if you can find it.

Try these two links:

Rerouting vacuum lines to have recirculated a/c at all times?

w123 recirculation "flap"

The text describing which of the 5 electric vacuum valves to select somehow got cut from the first post. But that information appears in the 2nd thread linked above. I deny any relationship with the guy that wrote the original article.

Quote:

Originally Posted by remotemark

As the 123 doesn't have a recirc button, how do you know when it goes into recirc?

IIRC, the CCU decides whether to invoke recirc based on the temperature delta between the setpoint and the vehicle interior. On a 123 there is no way to force recirc, you are at the mercy of the climate control logic.

funola · #19 06-04-2014, 12:54 PM

Quote:

Originally Posted by jcyuhn

Try these two links:

Rerouting vacuum lines to have recirculated a/c at all times?

w123 recirculation "flap"

The text describing which of the 5 electric vacuum valves to select somehow got cut from the first post. But that information appears in the 2nd thread linked above. I deny any relationship with the guy that wrote the original article.

IIRC, the CCU decides whether to invoke recirc based on the temperature delta between the setpoint and the vehicle interior. On a 123 there is no way to force recirc, you are at the mercy of the climate control logic.

Thanks for the links.

Slightly off topic, has anyone tried to clean out the evaporator by reversing the blower direction (change polarity) and help it along with a leaf blower to clean it from inside out?

eatont9999 · #20 06-06-2014, 06:34 PM

Quote:

Originally Posted by funola

Thanks for the links.

Slightly off topic, has anyone tried to clean out the evaporator by reversing the blower direction (change polarity) and help it along with a leaf blower to clean it from inside out?

I have not tried that one.

Ever since I bought an inspection camera, I have been wanting to use it. I might drop the blower and shove that camera down in there and see what the evap looks like. If there are leaves and things in there, I will attach a piece of heater hose to my vacuum and shove that in there, then finish it up with some coil cleaner.

lakerat · #21 06-08-2014, 09:20 PM

About two months ago I installed a Kilma Sanden conversion kit and stuck with stock condenser and R12. When ambient outside temps were in low 80's I was seeing 34 degrees at center vent now that temp has reached 95 I am lucky to see 48 degrees, I am having same problem the evap does not get cold enough for ETR sensor to cycle compressor. I decided to purchase the kit with TXV and dryer. Everything is functioning properly Fresh/recirculated air flap, heater valve is closing, main air flap is working, electric fan turns on. Aux pump is off, sight glass is clear and pressures measure correctly, no CC belt slip. Does
anybody have any Ideas? Thanks

TheDon · #22 06-08-2014, 10:24 PM

I totally need to do the recirc mod, it would help a lot at keeping the interior cool.

vstech · #23 06-08-2014, 11:20 PM

Quote:

Originally Posted by lakerat

About two months ago I installed a Kilma Sanden conversion kit and stuck with stock condenser and R12. When ambient outside temps were in low 80's I was seeing 34 degrees at center vent now that temp has reached 95 I am lucky to see 48 degrees, I am having same problem the evap does not get cold enough for ETR sensor to cycle compressor. I decided to purchase the kit with TXV and dryer. Everything is functioning properly Fresh/recirculated air flap, heater valve is closing, main air flap is working, electric fan turns on. Aux pump is off, sight glass is clear and pressures measure correctly, no CC belt slip. Does
anybody have any Ideas? Thanks

Report ambient temp, humidity, system pressures, and line temps... Specifically temp of line exiting evaporator, and line entering receiver. Also rpm of engine, and vent temp

lakerat · #24 06-08-2014, 11:38 PM

95 degrees,50% humidity, all new hoses suction and high pressure all new O-rings no leaks, 1800rpm 23 psi and 230 psi all gauges are steady, Sanden SD7H15 compressor, I do not have any accurate way to measure line temps, sight glass is perfectly clear. I flushed all components twice hoses cond. and evap blew clean air and pumped down with 8cfm Robinair for 24hrs and electronically checked for leaks.

cbjukraine · #25 06-09-2014, 12:31 AM

lakerat, I'm in pretty much the same boat. I'm seeing about the same vent temps. After about 30 minutes on the freeway at 90s ambients, I'm lucky to see 47 degrees at the vent. And I have a mod switch from a 190D that shuts the outside air door, so I'm getting theoretically 100% cabin air. If I set the fan to low, the temps lower and cycle the compressor, but not on the "AUTOM" setting.

I think my problem is perhaps too much oil in the system, as I didn't flush the system when I installed the Sanden compressor. My evaporator may oil logged... but I don't have a refrigerant recovery machine to get the r12 out.

That or maybe the Sanden doesn't have the same capacity as the R4?

Quote:

Originally Posted by lakerat

About two months ago I installed a Kilma Sanden conversion kit and stuck with stock condenser and R12. When ambient outside temps were in low 80's I was seeing 34 degrees at center vent now that temp has reached 95 I am lucky to see 48 degrees, I am having same problem the evap does not get cold enough for ETR sensor to cycle compressor. I decided to purchase the kit with TXV and dryer. Everything is functioning properly Fresh/recirculated air flap, heater valve is closing, main air flap is working, electric fan turns on. Aux pump is off, sight glass is clear and pressures measure correctly, no CC belt slip. Does
anybody have any Ideas? Thanks

ROLLGUY · #26 06-09-2014, 03:26 AM

Quote:

Originally Posted by cbjukraine

That or maybe the Sanden doesn't have the same capacity as the R4?

I believe with the new hoses (at least the ones that I sell), and a Sanden, the volume is a little less than the R4 compressor and hoses. Always start a little under charged, and go up from there. It is nice to have a local A/C shop that is willing to work with you. I am fortunate to have such a shop. I bring about a car a week there to vac/charge, and they work with me on the price and help find/fix leaks if any. I am sure you could find a place that will recover a couple ounces and credit you for next time....Rich

lakerat · #27 06-09-2014, 11:55 AM

I replaced the suction hose from compressor with a MB hose but I noticed the rubber hose before it couples to steel was smaller in dia then the original hose and when I first noticed it I thought it might collapse under suction and had the second suction hose that goes to TXV valve rebuilt with Goodyear galaxy hose which looked to be same size as original size hose, maybe the one I bought from MB is the problem?