1972 Duster Build with my Daughter

MaxPF said
Hmm, curious. I'm guessing it isn't an NOS unit? Just out of curiosity, are the drier fittings o-ring or flare?

What were the pressures before and after you removed refrigerant?

Good to hear! Yeah, voltage drops caused by multiple switches and small wiring are a common cause of clutch slippage. Again, make sure you are using 14ga. wire for all the power runs between the battery, relay, and coil. Make sure you're using a high quality 30A or 40A relay, preferably in a sealed socket. Don't forget a solid ground as well. And make sure there is a flyback diode reverse-biased across the coil. Also, don't forget to fuse the power lead at the battery. You don't want a short causing an under-hood fire!

Here's a complete 40A relay and sealed socket kit: Home » Shop » Relays / Fuses » Tyco MCP 6.3 (630) High Current Sealed Relay Kit SPDT 40 AMP

This is a new kit. It is actually cheaper than the Delphi (now Aptiv) 30A relay kit. The kit comes with a high quality relay, not cheap junk. Ive used it to run electric fans and blower motors, and havent had one die yet. Again, make sure you have a 3A flyback diode installed across the coil terminals, reverse-biased, to protect the relay contacts from arcing caused by the energy stored in the coil's magnetic field.

A nice sealed fuse holder for ATO (blade type) fuses: Home » Shop » Relays / Fuses » GM / Delphi - Sealed Fuse ATO Holder Kit - ( 18 - 14 gauge )

Mount the fuse holder as closely as possible to the battery terminal, with as short of a wire as possible on the battery side of the fuse holder. A 20A fuse should be sufficient for the clutch coil circuit.

FWIW, I've bought connectors from Ballenger many times with no issues. They're not the cheapest place, but they're not out of line either, and the convenience of their kits makes it worth the few extra bucks if you're buying one-sees or two-sees.

It is not factory... I was replacing parts so much I started using cheap auto parts store ones. Once I get this this truly workings I need to move the drier to the correct '72 position and get a few lines made. When I do that I will find a real mopar one and have it restored. They are o-ring style dryers. This was after a 75 mile drive in 90 degree temps then heat soaking in the driveway for about 10 minutes. Low side was around 50 high was around 260, at idle. Reved it would drop down to around 35. The clutch would slip trying to get it started after a few seconds of off at idle (first clue it was likely voltage drop). I set it so it was about 32 low and 225 high at idle and let the low drop to the low 20s when reved up. Once I got there the refrigerant was about where it really should have been and the clutch would engage but you would tell it was on the edge of not wanted to quite grab hard. A jumper wire from the battery to the clutch made it clearly "snap in hard". Thanks for the links. I put a cheap auto parts relay (bought 2 for the trip this weekend just in case) and yes I need to replace it with quality parts if this ends of solving the problems.

Thanks,
Jim