A6 compressor identification
#1
03-30-2017, 08:59 AM
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A6 compressor identification
A bit of trivia for most....unless you're faced with compressor replacement, perhaps.
The GM/Harrison A6 compressor was used for many years of Jaguars and contrary to popular belief they are not "all the same". There were several sub-variations in A6 design over the years but the only one likely to be significant to Jag owners will be "Superheat type" and "HSLP Type". This refers to the type of protection circuit used to open the circuit and shut down the compressor in the event of Freon loss.
Jaguar changed from "Superheat" to "HSLP" circa late 1986/early 1987 calendar year. "HSLP", by the way, stands for "High side, low pressure".
The Superheat system is easily identified by the presence of the 3-terminal "thermal limiter" fuse attached to or near the compressor bracket. (pic attached) The HSLP system does not use this device.
Some vendors/catalogs do not differentiate between the two systems or do so in vague terms. To ensure you're getting the correct compressor is quite easy. In the attached pic of the rear of the compressor you'll see the two main ports for the A/C hoses. Below those you'll see a switch held in with a snap ring. Remove the snap ring and the switch....it just wriggles out. Inside the now-exposed port you'll see a small hole. If the hole is dead-center in the port, that's a "Superheat" type compressor. If the hole is offset to the side, it's the "HSLP" type.
(Replacement compressors are shipped with a blanking plug in place...the idea being that you'd remove the switch from the old compressor and transfer it to the new. So, if you're looking at a new compressor, you'll be wriggling out a blanking plug, not a switch)
You can't mix-n-match here. The protection circuit won't work and, AFAIK, an incorrect switch cannot physically fit.
It's easy (and common) to convert from a Superheat system to the HSLP system. The wiring change is dead simple. So, if you have a Superheat system and somehow end up with an HSLP compressor....no worries.
Converting the other way around....from HSLP to Superheat.... isn't as easy (you'll have to buy or makes the wiring) nor particularly desirable. I doubt that anyone ever does so.
Also, the back plates of the compressor could be swapped over.....but I suspect this is beyond the scope (or desire) of most owners or mechanics
Cheers
DD
The GM/Harrison A6 compressor was used for many years of Jaguars and contrary to popular belief they are not "all the same". There were several sub-variations in A6 design over the years but the only one likely to be significant to Jag owners will be "Superheat type" and "HSLP Type". This refers to the type of protection circuit used to open the circuit and shut down the compressor in the event of Freon loss.
Jaguar changed from "Superheat" to "HSLP" circa late 1986/early 1987 calendar year. "HSLP", by the way, stands for "High side, low pressure".
The Superheat system is easily identified by the presence of the 3-terminal "thermal limiter" fuse attached to or near the compressor bracket. (pic attached) The HSLP system does not use this device.
Some vendors/catalogs do not differentiate between the two systems or do so in vague terms. To ensure you're getting the correct compressor is quite easy. In the attached pic of the rear of the compressor you'll see the two main ports for the A/C hoses. Below those you'll see a switch held in with a snap ring. Remove the snap ring and the switch....it just wriggles out. Inside the now-exposed port you'll see a small hole. If the hole is dead-center in the port, that's a "Superheat" type compressor. If the hole is offset to the side, it's the "HSLP" type.
(Replacement compressors are shipped with a blanking plug in place...the idea being that you'd remove the switch from the old compressor and transfer it to the new. So, if you're looking at a new compressor, you'll be wriggling out a blanking plug, not a switch)
You can't mix-n-match here. The protection circuit won't work and, AFAIK, an incorrect switch cannot physically fit.
It's easy (and common) to convert from a Superheat system to the HSLP system. The wiring change is dead simple. So, if you have a Superheat system and somehow end up with an HSLP compressor....no worries.
Converting the other way around....from HSLP to Superheat.... isn't as easy (you'll have to buy or makes the wiring) nor particularly desirable. I doubt that anyone ever does so.
Also, the back plates of the compressor could be swapped over.....but I suspect this is beyond the scope (or desire) of most owners or mechanics
Cheers
DD
Last edited by Doug; 03-30-2017 at 10:57 PM.
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#2
03-30-2017, 09:45 AM
Veteran Member
#3
03-30-2017, 10:47 AM
Actually, when I was doing my AC conversion, I purchased a HSLP compressor, because I could not get a Superheat A6 locally.
I just switched the backplate from my leaking Superheat A6 to the HSLP compressor using a new "bevelled" o-ring.
My old compressor leaked because of a faulty o-ring. When I ordered and replaced the backplate o-ring, I over tightened one of the 3/4 nuts holding the backplate to the compressor and the stud that is spot welded on to the compressor body broke away.
Whether I over tightened or whether the weld was weak is up for debate.
I say weak or deteriorated weld. lol
So far, so good
I just switched the backplate from my leaking Superheat A6 to the HSLP compressor using a new "bevelled" o-ring.
My old compressor leaked because of a faulty o-ring. When I ordered and replaced the backplate o-ring, I over tightened one of the 3/4 nuts holding the backplate to the compressor and the stud that is spot welded on to the compressor body broke away.
Whether I over tightened or whether the weld was weak is up for debate.
I say weak or deteriorated weld. lol
So far, so good
#4
03-30-2017, 12:10 PM
Veteran Member
Rock Browning of RetroAir Inc. now sells a lighter version of the Harrison in either black or Chromed, (yes, CHROMED). Suitable for R12 or R134a. A friend in Australia ordered 6 of them.
