Friends of the Professional Car Society - Official Website of the Professional Car Society, Inc.Friends of the Professional Car Society - Official Website of the Professional Car Society, Inc.



Go Back   Friends of the Professional Car Society - Official Website of the Professional Car Society, Inc. > Professional Car Discussion > Technical Discussion Forum

Technical Discussion Forum For the discussion of technical questions about Professional Cars and their repair and maintenance. Posting in this forum is limited to PCS Members and / or Site Supporters. We encourage all website users to become members of the Professional Car Society and / or become Site Supporter.

Reply
 
Thread Tools Display Modes
  #1  
Old 07-21-2019, 09:11 PM
Chris Elzie Chris Elzie is offline
Website Member
 
Join Date: Dec 2009
Location: Coldwater MS 38618
Posts: 245
Thanks: 21
Thanked 426 Times in 138 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default Rear Ambulance A/C

My ambulance has 2 switches for the ac, one turns on the fans and the other Im not sure beacuse nothing happens. Its a 76 S&S Professional. Does anyone have a basic layout on how the rear ac works? Is there a compressor of some sort in the unit?
Reply With Quote
  #2  
Old 07-21-2019, 10:09 PM
John ED Renstrom's Avatar
John ED Renstrom John ED Renstrom is offline
PCS Member - Elected Director 2017-2020
 
Join Date: Mar 2009
Location: Hot Springs SD 57747
Posts: 11,817
Thanks: 4,260
Thanked 15,371 Times in 6,479 Posts
Groans: 2
Groaned at 3 Times in 3 Posts
Default

The front ac has to be on. The unit is just anothef evaporater. So if the ac in the car works and the fan comes on you should have ac in the rear unless someone removed the lines.
__________________
drop in for coffee anytime
Reply With Quote
  #3  
Old 07-26-2019, 04:56 PM
David Henry's Avatar
David Henry David Henry is offline
PCS Member
 
Join Date: Feb 2016
Location: Fruitport MI 49415
Posts: 226
Thanks: 652
Thanked 359 Times in 178 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

So speaking of S&S A/C the compressor doesn’t kick on unless you jump it in my 74. Is there a relay or something that might not be working. It does have that dial thermostat in the front...
__________________
Current owned:
1974 Sayers and Scovill Professional Ambulance
Previously owned:
1973 Miller Meteor Lifeliner Ambulance
Future ownership:
1971-1973 Wayne Sentinel Suburban Ambulance
Reply With Quote
  #4  
Old 07-26-2019, 09:43 PM
John ED Renstrom's Avatar
John ED Renstrom John ED Renstrom is offline
PCS Member - Elected Director 2017-2020
 
Join Date: Mar 2009
Location: Hot Springs SD 57747
Posts: 11,817
Thanks: 4,260
Thanked 15,371 Times in 6,479 Posts
Groans: 2
Groaned at 3 Times in 3 Posts
Default

Try recharging it.the low pressure switch will not let the compressor come on when you jump it ther is enough pressure t o keep it closed.
__________________
drop in for coffee anytime
Reply With Quote
  #5  
Old 07-27-2019, 04:12 PM
David Henry's Avatar
David Henry David Henry is offline
PCS Member
 
Join Date: Feb 2016
Location: Fruitport MI 49415
Posts: 226
Thanks: 652
Thanked 359 Times in 178 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

Ok did a leak detection and none noted. The system was charged as doing the change from R12 to current standard juice.
__________________
Current owned:
1974 Sayers and Scovill Professional Ambulance
Previously owned:
1973 Miller Meteor Lifeliner Ambulance
Future ownership:
1971-1973 Wayne Sentinel Suburban Ambulance
Reply With Quote
  #6  
Old 07-27-2019, 06:21 PM
Paul Steinberg Paul Steinberg is offline
PCS Past President / Senior Website Administrator
 
Join Date: Mar 2009
Location: Woodstock CT 06281
Posts: 6,631
Thanks: 7,300
Thanked 12,422 Times in 4,068 Posts
Groans: 0
Groaned at 9 Times in 9 Posts
Default

Quote:
Originally Posted by Chris Elzie View Post
My ambulance has 2 switches for the ac, one turns on the fans and the other Im not sure beacuse nothing happens. Its a 76 S&S Professional. Does anyone have a basic layout on how the rear ac works? Is there a compressor of some sort in the unit?
If there are 2 switches in the rear, the most likely situation is that one is for the fan, and the other turns the compressor on, if it hasn't already been in A/C mode in the drivers compartment. Usually the fan is a rotary switch with more than one speed.
If your compressor isn't starting, then check to see if it has the thermal overload protection device somewhere in the electrical line. If this is bad, then the system will not start. I suggest that you check your factory service manual for location and testing procedure.
Attached Images
 
Reply With Quote
  #7  
Old 07-27-2019, 06:31 PM
Paul Steinberg Paul Steinberg is offline
PCS Past President / Senior Website Administrator
 
Join Date: Mar 2009
Location: Woodstock CT 06281
Posts: 6,631
Thanks: 7,300
Thanked 12,422 Times in 4,068 Posts
Groans: 0
Groaned at 9 Times in 9 Posts
Default

Quote:
Originally Posted by David Henry View Post
Ok did a leak detection and none noted. The system was charged as doing the change from R12 to current standard juice.
How was the leak detection done? If they used an electrical probe, it doesn't always locate the leak. Best method is to install a can or two of Freon with black light dye or yellow dye. Your car has a very large system, and a leak can be anywhere in the system, including the rear evaporator which is difficult to do a leak detection on. On large systems, I pull a vacuum for a couple of hours, and then add a two cans of Freon with dye, and then pressurize the system with nitrogen, to push the dye to all points of the system. Sometimes even that doesn't work, and you have to start breaking the system apart and install all new seals, and assume that is the problem. If that doesn't cure the problem, then you have to put the full charge of nitrogen into the system, and using a special soap mixture, start spraying the hoses, and hope that you will find the leak. It is time consuming, and you use up quite a bit of expensive supplies before you can find the leak.
Reply With Quote
  #8  
Old 07-27-2019, 08:09 PM
Chris Elzie Chris Elzie is offline
Website Member
 
Join Date: Dec 2009
Location: Coldwater MS 38618
Posts: 245
Thanks: 21
Thanked 426 Times in 138 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

The ac in the front compartment works fine, Im just not getting any cooling in the back. I was thinking the line might be stopped up somehere, because all the hoses are hooked up.
Reply With Quote
  #9  
Old 07-27-2019, 10:05 PM
John ED Renstrom's Avatar
John ED Renstrom John ED Renstrom is offline
PCS Member - Elected Director 2017-2020
 
Join Date: Mar 2009
Location: Hot Springs SD 57747
Posts: 11,817
Thanks: 4,260
Thanked 15,371 Times in 6,479 Posts
Groans: 2
Groaned at 3 Times in 3 Posts
Default

The valve in the rear evaporator may be bad.the 134a is what you charged it with? Most of them of have seen were a cobble of factory hoses hooked togeather. One may want to change them to new hose. They could be broken down inside.
__________________
drop in for coffee anytime
Reply With Quote
  #10  
Old 07-27-2019, 11:08 PM
Paul Steinberg Paul Steinberg is offline
PCS Past President / Senior Website Administrator
 
Join Date: Mar 2009
Location: Woodstock CT 06281
Posts: 6,631
Thanks: 7,300
Thanked 12,422 Times in 4,068 Posts
Groans: 0
Groaned at 9 Times in 9 Posts
Default

Quote:
Originally Posted by Chris Elzie View Post
The ac in the front compartment works fine, Im just not getting any cooling in the back. I was thinking the line might be stopped up somehere, because all the hoses are hooked up.
If the hoses were "stopped up", whatever was in the hoses, would have killed the front air conditioning system. Most likely, the expansion valve has failed. It can't be fixed without draining the system of Freon, and tearing into it. I suggest that you have a professional air conditioning service person take a look at the system.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
1950-'53 Cadillac Superior Ambulance Rear Door Channing Spencer eBay Listings Discussion Forum 0 06-21-2017 03:33 PM
1960 Cadillac Ambulance rear door Joe Melanson Craigslist Listings Discussions Forum 7 09-16-2013 09:23 PM
1973 Superior Cadillac Ambulance rear bumper Pat Post Wanted 7 08-15-2012 11:03 AM
'69 M-M Ambulance Rear Bumper Paul Steinberg Wanted 6 02-17-2011 03:16 AM


All times are GMT -4. The time now is 08:49 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.