A/C component difference?

[Irish Pride]

I'm in the process of acquiring all the parts needed to replace the A/C in the White 89 that i just bought. So far I have everything needed except the Discharge Hose which is on order and should be arriving soon. What I have is -

Motorcraft reman Compressor
New R134 Accumulator (94-95) #55641
New R134 Discharge Hose (94-95) on order #YF2021
New 89-93 Suction Manifold #YF2022
New 89-93 Discharge Manifold #YF1572
New Liquid Line/Orifice Tube #55722

From everything that I've read, there shouldn't be any issues installing all this stuff. My question is, what is the difference between the 89-93 Manifolds and the 94-95 Manifolds? From all the diagrams I can pull up at work everything looks the same. Are the seals different because of 134 v R12?

 

[luigisho]

It's been a long time since I tackled one of these. I forget how far the manifold extends from the compressor. The differences I can recall from r12 and r134a is high pressure cutoff switch in the 134 and maybe (hardly remember if this is true or not) the condenser is bigger. So I am wondering of there is a plumbing length issue as I think GenI and II all used the nippondenso 10p15f compressor. Same compressor then the mating surface at the manifold should be the same. Did the routing length change with the 134a or with the addition of the ATX underhood spacing?

Hopefully Perry is still popping in on the board as he was pretty good with the ac stuff way back

 

[rubydist]

two of the lines have different part numbers, but from my comparing them it was only due to the different charge port configuration for the R134a compared to the R12.
the condensor and evaporator are the same parts.
the compressor did not change according to my research, although the part number changed because it has the different oil.
the amount of refrigerant charge was reduced when they went to R134a.
when you put on the 94/95 high side line, you will need to plug a high pressure cutoff switch into the line, even if you don't wire up any ability for it to shut off due to over pressure. I do recommend that you allow it to cycle off due to over pressure, as I have experienced blowing out refrigerant from the over-pressure valve after converting, if the system pressure was just a little high.

 

[Irish Pride]

The new high side line will have a port for the High Pressure switch? I'm assuming there isn't a pigtail on the 89 harness for it?

 

[rubydist]

Yup, the R134a line with have the high pressure port. The R12 systems did not have any high pressure cutout, so no wiring.

The typical Ford high pressure switch has two switches in it - one that is closed with normal pressure and opens when the pressure is too high. The 2nd is the opposite, normally open and closes when the pressure is too high. What I would be tempted to do is to use the normally closed switch and put that in series with the wire that goes to the a/c compressor clutch - when the pressure is too high, it opens the switch which opens the circuit to the clutch; then when the pressure drops down the clutch turns on again. iirc, those switches have a fair amount of hysteresis, so they stay open a while, so it doesn't cycle the clutch too quickly.

That switch and the connector are pretty standard Ford parts, so a quick trip to the jy should get you a switch and pigtail to use.