Do I need to change expansion valve?

[Sixpactogo]

When I built my 68 Charger back in 2015 with a 6.1 Hemi, it had a factory A/C that didn't work. I had the evaporator pressure tested when I had everything apart and rebuilt the heater box. I bought a new condenser, expansion valve, dryer (all stock R12 68 Charger parts) and all new hoses O rings and plumbing.
I used the factory installed compressor that came on my 06 SRT engine. I then took it to a refrigeration shop and had them vacuum and charge the system with the 134. It has been cooling great with zero problems since then thankfully.

 

[YY1]

Your pressures are similar to mine, but ambient temperature, relative humidity and all play into the equation. Check your drain again as condensation on the outside of the box could be coming from a partially obstructed drain. Sounds like your system is working great.

Yes, it is except for the outside of the box condensation dripping on the carpet.

External condensate drain is working fine.

There are droplets forming on the exterior of the box, and during turns, they run together and form drops heavy enough to drip off.

Kinda hate that I'm hijacking this thread....

But the AC was fine before the safety valve popped (of course something caused that to happen) while idling unattended for about 15 minutes.
Before that, it blew 40-ish degrees and I never had a external condensation issue on the plastic (fiber?) evaporator box.
I understand the coils are supposed to condense and that condensate goes out the drain hole on the firewall.

 

[Some Car Guy]

It’s fine, I find this all fascinating since this is the first car I’ve ever fooled with the ac on. I’ve had a couple others that had the ac stripped out long before and that’s it. My second vehicle ever was a 77 d100 the dealer claimed ac worked good on. I made it about a mile from home when it started blowing warm and I just got used to not having it in anything.

 

[Some Car Guy]

How does the one tube of the expansion valve attach? the one end screws on, the one I’m wondering about looks to be stuck into the line.

 

[Sixpactogo]

I believe the one you are asking about is the temperature probe. It just slides into a well that is built into the tubing. The well is isolated from the system.

 

[Some Car Guy]

Ok good, thanks.

 

[gtx6970]

Finding quality exp valves can be tough.

If you can find one...use NOS Mopar.
Last year when I did my Coronet.

I got one from Oriellys. I think Murray brand???

Don't remember the pressures. But 40s at the vents was damn cold in the car in short order

Remember....charge the system to about 80% with 134

 

[RJRENTON]

The expansion valve sizing, beside the connection fittings sizes, is determined by the refrigerant used (the TXV controls the evaporator's exiting saturated refrigerant temperature or SUPERHEAT temperature). Too little refrigerant flow to the evaporator will result in insufficient cooling; conversely, too much refrigerant flow to the evaporator will result (usually) air side icing. The TXV is pressure balanced device using exiting refrigersnt pressure and exiting refrigerant temperature. The new systems use a pressure cycling control sydtem (cycling the compressor clutch on/off to maintain an average evaporator pressure) and a FIXED refrigerant metering orifice sized to prevent flooding and starvation of the evaporator. Esch refrigerant (example R134A) has a specific heat characteristic (ability to absorb and release heat) that's pressure and temperature dependent.
The old R12 refrigerant operates at different pressures and temperatures. The gas in the old TXV sensing element will likely not be compatible with the R134A resulting in less than ideal results. IF one has been successful in not replacing the TXV or eliminating it, the "DFL" factor may be applicable. Just my opinion of course......
BOB RENTON