W126 AC woes solved - Page 2 - PeachParts Mercedes-Benz Forum

Rooster300SD · #16 08-10-2012, 10:19 AM

WhiskeyDan, I would like to know how you attached the two condensers
together and how they & the fan mounted onto the car.
Should the PF be in front or behind the tube & fin?
A pix of the current install would be great.

Thanks,
Jeff

Whiskeydan · #17 08-12-2012, 09:01 AM

Quote:

Originally Posted by Rooster300SD

WhiskeyDan, I would like to know how you attached the two condensers
together and how they & the fan mounted onto the car.
Should the PF be in front or behind the tube & fin?
A pix of the current install would be great.

Thanks,
Jeff

Here's a small pic from my phone from the initial install. The aux fan is just setting there to check clearance with the grill.
Next chance I'll get some better shots.

vstech · #18 08-12-2012, 09:57 AM

totally not what I was picturing in my head.
so... what is the stock condenser doing? it's becoming a GIANT reciever. I'm assuming, the plumbing feeds the PF first, then the stock condenser.

Whiskeydan · #19 08-12-2012, 10:28 AM

Quote:

Originally Posted by vstech

totally not what I was picturing in my head.
so... what is the stock condenser doing? it's becoming a GIANT reciever. I'm assuming, the plumbing feeds the PF first, then the stock condenser.

.

Stock cond first then PF, stock rec/dryer is still used.

vstech · #20 08-12-2012, 12:11 PM

ahh, so you are using the PF as a subcooler. interesting. all liquid goes through the PF then. and it receives the already cooled liquid from the stock condenser. the large feed tubes from the PF act as a receiver, and the tiny passages of the PF perform a subcooling process. I follow this fine. in this manner, the PF passes little heat to the stock coil, so both operate very efficiently! good job.

vstech · #21 08-12-2012, 12:14 PM

as for subcooling, I've often imagined routing the condensate into a reservoir and routing the liquid line into it would aid in cooling the vehicle VERY WELL... but the condensate would damage the lines unless the heat exchange was fashioned out of stainless steel or similar... still it would work very well also...

ibenz · #22 08-12-2012, 01:07 PM

Quote:

Originally Posted by Whiskeydan

.

Stock cond first then PF, stock rec/dryer is still used.

have you thought of running dual PF condensors... or is it from a cost effective standpoint to keep with the stock one

Whiskeydan · #23 08-12-2012, 08:45 PM

Quote:

Originally Posted by ibenz

have you thought of running dual PF condensors... or is it from a cost effective standpoint to keep with the stock one

That might be an option for those with the pre-85 tube and fin condensers but, I think this is more than sufficient to reach the limits of the evaporator, TXV and pump. Any more and you'll be slugging the comp suction side with liquid although, the evap switch limits this if adjusted properly.
Plus, think about where that heat is going... straight thru the radiator. Now we have an issue of engine cooling...

This system is cost effective, easy install, works and can be put back stock for the purist MB buyer that lives in a cooler climate. No cutting, hacking required.

Whiskeydan · #24 08-12-2012, 09:00 PM

Quote:

Originally Posted by vstech

as for subcooling, I've often imagined routing the condensate into a reservoir and routing the liquid line into it would aid in cooling the vehicle VERY WELL... but the condensate would damage the lines unless the heat exchange was fashioned out of stainless steel or similar... still it would work very well also...

We have a guy here that uses his windshield washer tank and a shurflow pump to mist the condenser on a W123. I ask if he had thought about scavenging the condensate to replenish the tank.

I worry about deposits on the condenser over time.

Whiskeydan · #25 08-12-2012, 09:08 PM

Quote:

Originally Posted by vstech

ahh, so you are using the PF as a subcooler. interesting. all liquid goes through the PF then. and it receives the already cooled liquid from the stock condenser. the large feed tubes from the PF act as a receiver, and the tiny passages of the PF perform a subcooling process. I follow this fine. in this manner, the PF passes little heat to the stock coil, so both operate very efficiently! good job.

Yes.

The stock is better defined as a 'pre-cooler' since it has a difficult time condensing R134. (Notice bubbles in the receiver/dryer sight glass.)

The PF then fully condenses R134 to a liquid state and fills the receiver/dryer to supply the expansion device which flood the evap coil.

SD Blue · #26 08-13-2012, 02:22 PM

Outstanding! How did you bridge the two condensers together? Did you have a hard line manufactured or did you just use a hose assembly, such as the one for the condenser to rec/dryer?

This also appears to be a very economical and working method to convert to R134. (Which is very beneficial to those of us who had conversions done by previous owners.)

Do you think this will cause any issues when operating the compressor in cooler temps for defrost?

Thanks WhiskeyDan!

Codifex Maximus · #27 08-13-2012, 10:04 PM

Nice. I wouldn't mind having icicles hanging off my nose in mid summer.

I assume this mod requires extra R-134a and maybe extra oil. Would it put more stress on the compressor?

I salute you!

Whiskeydan · #28 08-13-2012, 10:07 PM

Quote:

Originally Posted by SD Blue

Outstanding! How did you bridge the two condensers together? Did you have a hard line manufactured or did you just use a hose assembly, such as the one for the condenser to rec/dryer?

This also appears to be a very economical and working method to convert to R134. (Which is very beneficial to those of us who had conversions done by previous owners.)

Do you think this will cause any issues when operating the compressor in cooler temps for defrost?

Thanks WhiskeyDan!

Sam, It's a simple disconnect of the stock evap to rec/dryer fitting and connect new hose there.
Outlet of PF (new hose) goes to R/D. Stock cond to R/D hose is unused.

If the evaporator temp switch is working properly there should not be any issues in cool wx.

One can 'gamble' and get lower vent temp via bypassing or by adjusting the switch to a lower temp but, you take the chance of slugging the compressor with liquid refrigerant.

Should I offer a kit???

Dubyagee · #29 08-13-2012, 10:12 PM

Someone say kit?

vstech · #30 08-14-2012, 02:31 AM

I was looking at my 87TD today for likelihood of this mod... temps in the cabin creep upwards to uncomfortable when it's over 95 outside (nearly every day so far this summer....) it's still got the original 87condenser, and I have a 93 updated one... along with the dual fan setup... so I'm contemplating both, or just one vs the other... I don't think there is any worry of slugging the compressor with this mod, unless the evap switch is defective. the txv's job is to maintain correct heat in the return line, so aiding the subcool in the liquid should be a no brainer for function... but the correct charge is now difficult to attain. the 80% rule would not apply to this subcooled system. likely it'll be at or even above the stock R12 volume. getting a measurement of the actual subcool temp would be wise. for this you'd need a fitting on the line exiting the receiver to get an accurate liquid line pressure for the subcool mark, and an accurate line thermometer. I'd shoot for 6 degrees of subcool, and not go over 9 or risk overcharge.