Which one is which? 90 vdp

I have the old fittings, I'm trying to upgrade to R 134a. Haynes and the R134a both advise heavily not to try and put it in the low side. In the Haynes it says the retro kit will only fit on the high side. Ahhhh, how can that be? Both fittings on my engine are the same, the one by the firewall and the one by the radiator. The adapter on the retro kit will fit either.

Which is the high, which is the low? I'm guessing the one fitting by the firewall is the high? Anyone know? If I guess right, I'm playing Belmont tomorrow.

 

On my '91 the low side is at the firewall and the high at the radiator, my caps are still intact indicating high and low sides. Don't know if 90 to 91 are different but that's how mine is. Hope this helps.

Charlie

 

Excellent. They are not different. I have the original caps, they are not marked.

 

low side on my 93 is closest to firewall

 

The way I remember it is the low side goes from the firewall(evaporator) to the compressor and the high side goes from the compressor to the condensor.

 

Thank you. Low side is at the firewall. A/C working again in the White 90 sovereign. Black 90 VDP and my 92 XJS blowing hot. 1 out of 3 I'll take.

 

COOL!
Charlie

I wish mine were working, it's hot here!