Air conditioning

#1
Hi all
Just got the Duchess back after replacement of the heater/cooler unit blower which was completely knackered after 50 years. Great job plus got thermostatically controlled internal temperature- a bonus. Incidentally does anyone know of a reputable company who will do a dyno test on an automatic car. The few I have contacted will not work on automatics.
Thanks.
 

falkor

Active Member
#2
very few P6s were fitted with A/C , most were not so the whole subject of A/C doesn't receive a lot of attention quite understandably. however I just bought a P6 which was fitted with A/C when it was made in 1976 , the garage I took it to for MOT are scratching their heads over the A/C and say it is not 1 of the 3 types of A/C that they know/ work on. the A/C isn't working and the garage are unable to regas it as it is not 1 of the 3 types of A/C that they know/ work on
 

roverp480

Active Member
#3
I am fairly certain the gas used in the 70's is no longer available (Freon etc) but I did get a early Discovery changed to the later gas, I think there can be a problem with the seals. It was done at a specialist air con firm
 

Demetris

Well-Known Member
#4
If the garage was talking about refrigerant compatibility, then yes, the original system is not compatible with the current refrigerants. However, it can be converted. If you intend to make full use of the system, then i suggest to replace the original York compressor with a modern type, like Sanden. These are physically lighter, much more efficient, and run much more smoothly than the old piston type. In this way it will be also compatible with the newer refrigerant R-134a. There are even ready made conversion brackets for this. If you want to retain the originality of the system, there are still new York compressors that are compatible with R-134a, but as far as i know this solution will be more expensive. Finally you have to renew all the rubber hoses with new ones that are also compatible with R-134a. The reason for doing so is that the later refrigerant has a smaller molecule and can escape very easily from the older hoses. A few years ago, when i did the retrofit in my Rover, there was someone on ebay selling conversions kits to R-134a for the Rover P6B.
 

clive P62

Active Member
#5
I've retro fitted a air con system into my friends 3500s 12 years ago using 134 gas and using the York compressor and the later type oil.
Kept original pipes , have only had to regas / top up 3 times in that time.( Not bad considering new cars usage of gas )
Due to the later refrigerant the amount added is less than the R 12 gas it replaces.
 

colnerov

Well-Known Member
#6
If the garage was talking about refrigerant compatibility, then yes, the original system is not compatible with the current refrigerants. However, it can be converted. If you intend to make full use of the system, then i suggest to replace the original York compressor with a modern type, like Sanden. These are physically lighter, much more efficient, and run much more smoothly than the old piston type. In this way it will be also compatible with the newer refrigerant R-134a. There are even ready made conversion brackets for this. If you want to retain the originality of the system, there are still new York compressors that are compatible with R-134a, but as far as i know this solution will be more expensive. Finally you have to renew all the rubber hoses with new ones that are also compatible with R-134a. The reason for doing so is that the later refrigerant has a smaller molecule and can escape very easily from the older hoses. A few years ago, when i did the retrofit in my Rover, there was someone on ebay selling conversions kits to R-134a for the Rover P6B.
Hi, Things have moved on again to the use of R1234yf, despite initial resistance by Mercedes Benz over flammability concerns. R1234yf is more expensive than R134a and production of R134a is being maintained for now but will be reduced over time, so the price is likely to rise as well. R134a can be replaced by R1234yf but there are compatibility issues with oils and hoses.

Colin
 

clive P62

Active Member
#7
Yes a new machine required so as to non contaminate either gas, been in use since approx 2014 , and the cost of refrigerant now !!!!!!
We had to get the new machine at the dealer I worked at.
 

Demetris

Well-Known Member
#8
I've retro fitted a air con system into my friends 3500s 12 years ago using 134 gas and using the York compressor and the later type oil.
Kept original pipes , have only had to regas / top up 3 times in that time.( Not bad considering new cars usage of gas )
Due to the later refrigerant the amount added is less than the R 12 gas it replaces.
I guess it doesn't harm to try that as a cheap alternative, but a set of new hoses isn't that expensive really, and i expect that you had to exchange also the fill up / vaccum port fittings, in order to connect the R-134a machine to an R-12 system. Unless of course you cheated and modified / adapted the fittings of your machine!
 

clive P62

Active Member
#9
R 12 fittings as original, my A C machine is a old type with sight glass so I can see the amount of refrigerant added.
Can use either gas as I have 2 sight glasses for both gasses.
Apparently the older pipes that were run on mineral oil help seal against 134 seepage.
New pipes as you said is the best way to go but I wanted it to look totally original.
It's been totally reliable even with the old type York compressor which I know does seep a bit due to its design.
Washed out the evaporator, fitted new condensor using original fixings.
New type expansion valve for 134 and looks identical to the old one. New reciever dryer unit .
Rebuilt compression and added the later pag 150 oil if I can remember.
 

Demetris

Well-Known Member
#10
Do you reckon that a new expansion valve would be essential for the new type refrigerant? This is one part that i retained from the old installation along with the evaporator, without any obvious issues.
 
Top