Author Topic: Installing AC expansion valve  (Read 1314 times)

johngmm

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Installing AC expansion valve
« on: July 05, 2015, 12:33:05 PM »
I have just replaced the AC compressor and receiver drier and am about to replace the expansion valve. (65 deville).   I've never done this job before so am unfamiliar with how things go but on looking at the existing expansion valve on the car, it looks as though the pigtail (bulb?) is held in place by some sort of black putty substance.  What is this stuff and where can I buy.  Many thanks, John

Re: Installing AC expansion valve
« Reply #1 on: July 05, 2015, 04:22:26 PM »
 are calling black putty. The bulb should be installed parallel to the suction line if it is  the straight type, or around the suction line if you have one with a curved bulb. The purpose of the bulb is to sense the suction line temperature, and the black material (available as "perma-gum" or "press tight") is to insulate the bulb from the heat in the engine compartment.  Be careful as the thermal bulb and capillary tube attached to it are rather fragile and will break if handled roughly.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline Scot Minesinger

  • Posts: 6004
Re: Installing AC expansion valve
« Reply #2 on: July 05, 2015, 06:21:57 PM »
That black stuff is a tape sold by USA Parts for low cost (under $10), call 304-724-6600 and ask for the "insulating black tape" for the air conditioning expansion valve bulb, you will need about 2'.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

johngmm

  • Guest
Re: Installing AC expansion valve
« Reply #3 on: July 05, 2015, 07:47:21 PM »
Thanks Greg and Scot.   The end of this thing (also by Murray) I have consists of about four or five coils about .375" dia.. and about .75" long.  I've seen types that have something like flattened tubing soldered at the ends of various lengths - all supposed to be suitable for my system -  and a fine mess you've got me into Olly LOL.  Better remove the thing and see what it looks like.  I guess the Perma-Gum or Press-tight is available at the local store.  I'd rather use this than tape.

Offline Jon S

  • Posts: 2561
  • Name: J. Schapiro
Re: Installing AC expansion valve
« Reply #4 on: July 05, 2015, 07:59:25 PM »
It's this stuff, but not sure where you find it today:

Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

Offline Scot Minesinger

  • Posts: 6004
Re: Installing AC expansion valve
« Reply #5 on: July 06, 2015, 11:03:01 AM »
Make sure what ever you use it is going to survive the under hood temperatures that approach 180'F.  This tape looks the most authentic and withstands the under hood temperatures.  This is all I use.  Used this on the 67 Deville that won first place GN2013 class 22.  The gum material is used on residential houses I understand (I'm an HVAC master mechanic in VA, MD, and etc.) but it may work.

It is called tape but is like 3/16" thick putty like and when molded the seams all disappear and it looks like the factory item when finished.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Offline Jon S

  • Posts: 2561
  • Name: J. Schapiro
Re: Installing AC expansion valve
« Reply #6 on: July 06, 2015, 11:18:15 AM »
Scot -

Good to know this stuff is still available.  I bought the pictured above back in the 1970's from Pontiac and it is still soft and pliable.  I used some on my 1973 Lincoln (Harrison AC) recently and the seams do disappear when molded and it does not stick to your hands.  Great stuff!
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

 

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