Dryer,

[325tbr]

i have an older dryer with 2 switches that i took out of my car but when i bought my new dryer it only had i low pressure switch. how do i wire in the new dryer with only one switch?

[DJB]

Do you have a new combined switch? Or are you trying to make your old switches work with the wrong drier?


64-53-1-466-051 Receiver drier 84-8/89
Two pressure switch ports, one pipe threaded and one o-ring sealed.
Originally had no Schrader valve, although better aftermarket driers
include one on the inlet side.
Original parts are compatible with R12 and mineral oil only, although most
are now aftermarket parts with desiccant that will work with R134a.

64-53-8-391-025 Receiver drier 9/89+
R12 and R134a compatible, part now listed in ETK as current for all
Two tab, has Schrader valve and one bolt-plugged switch port.
Some aftermarket parts use this number but have two bolt-plugged
switch ports to work with the older switches as well.

Note: Don't confuse the overpressure blow-out plug, which looks like a bolt with drilled and plugged hole, for a spot to install a pressure switch.

Both drier types have two mounting tabs from the factory. Some
aftermarket driers have three mounting tabs to handle additional
applications. For a neater installation with a three tab drier you need
64-12-1-379-221 6.3mm expanding nut $0.50/$0.43
07-11-9-916-970 ST6.3x19-c-z1 hex head screw $0.25/$0.21


BMW safety switches on old-style 051 drier
Wired lead white nylon "T" connector
61-31-1-365-510 Low pressure A/C pressure switch (replaced by 64 53 1 386 971)
Pipe threads, contacts close above 24-32psi, or 28-34psi
Wired lead white nylon "T" connector is the low-pressure switch, to prevent the
compressor from running with a low system

Two-pronged switch on drier
64-53-1-370-463 $10.15
Switch opens pressure exceeds 26.5 bar (385psi),
closes when pressure drops to under 21.2 bar (307psi)
Other specs list as 363-352psi - 320-284psi
O-ring sealed

New style pressure switch for new-style 025 drier
64-53-8-390-971 Note similar part number!
2 wire connectors w/ male pins in female black shell
Plug terminal, black 61-13-1-378-400 $1
This is only the plastic shell, which requires two waterproof
female contacts with the correct diameter molded rubber surround.
$43 at BMA, $5 w/ mating connector from your local boneyard

[325tbr]

the car has the old style switch and its a newer style dryier

[DJB]

Hmm, is this a new drier, or did you buy a used drier with a switch installed?

Buying a used drier is pretty much like buying a used oil filter that's been sitting in a mud puddle.

[325tbr]

nope the dryer is brand new but my car 1985 325e has a 325i motor so the old car has 2 pressure switches


http://www.realoem.com/bmw/diagrams/e/y/12.png



see number 19 and 20 but my new dryer doesnt have a place to put 20.
i hope this helps

[colin86325]

Just hook up either connector harness to the new dryer switch. The new dryer combines into a single switch the functions of the 2 separate switches.

[DJB]

Yes, you can hook the combined switch in place of either switch, and install a jumper on the other connector.

In early cars it doesn't matter at all, the pressure switches are wired in series right at the drier. In mid-production cars there is a sense wire after the high pressure switch. It goes to the evaporative temperature regulator module, but nothing useful is done with the signal.

I'm curious, why did you buy the new style drier? The old style drier is still available aftermarket for about the same price. The advantage of the new-style drier is that the new-style pressure switch supposedly has a slightly higher pressure cut-off setting, which is better for r134a but I've not seen a pressure rating that confirms the claim. The downside is that the new switch is $40+. (A minor advantage is that the new pressure switch screws onto a Schrader valve so you can replace the switch without depressurizing the system, but that's a rarely-used feature.)