Griffiths AC troubleshooting

[Tommy Z]

Before I reach out to Charlie, I thought I would try picking the big brains on this forum. Recently completed the installation of my Griffiths system on my 79' SC. Had to work through a couple of different places for the initial charge and ultimately wound up where I should of started, my amazing independent repair shop.

Finally got a good charge after he put the system on vacuum for 24 hours and charged the system with 32 ounces or so of R134A. Getting vent temps in the low 40's on a 96 degree 100%humidity day. My tech told me after leaving the car in full sun all day and with interior temps of almost 110 the system took 10 minutes or more to get decent temps out of the system, around high 50's to low 60's. Perhaps just the limitations of the system?

I picked it up last night and driving home was getting vent temps in the very low 40's, even kissed the high 30's for a minute. All is right and good on the planet and I'm feeling good! About 20 or 30 minutes into the drive the vent temps start rising to 60 degrees and once there immediately started dropping down to the low 40's again. This cycle repeated itself every ten minutes or so with it taking about 1-1/2 minutes to go from 42 degrees to 60 and back down to low 40's. Initially I thought the evaporator was freezing up but I can't imagine it would thaw out so quickly and return to low temps. Now I'm thinking the hi-low pressure switch might be kicking in and once it reaches 60 degrees, the clutch engages again and returns to making cold air.

I'm no engineer and certainly no expert so I'm hoping you all might have some insight. I'll reach out to Charlie eventually but I feel as though I had to hit him up so many times during the install that he would fine never to hear from me again!

Thanks in advance!

[walt]

Evaporator freezing up would be my first guess. What fan speed were you running when this was going on.

[Tommy Z]

Hi Walt, I retained the original fan selector switch so it was on speed 2 out of 3. My initial thought was the same but would the evaporator thaw out and start working again in under 2 minutes?

[GH85Carrera]

Reaching out to Charlie is the best option, He knows exactly what components he sold you, and has forgotten more about AC than most amateurs will learn.

My first question is just what system do you have? How many condensers? So you have his really neat temperature controller with the two LEDs that let you know if the compressor is running?

I have 4 condensers, his upgraded evaporator, and the hurricane blower and the variable speed fan speed knob and best of all, the temp switch that shows me if the compressor is cycling on and off.

In the Florida keys in July, my 911 sat outside in the full sun for a 1.5 hours while we pigged out on sea food. Get back in and within 10 minutes I was turning down the fan speed and turning up the temperature.

If really sounds like a low charge issue, but if it is a fresh charge, have the pro check the charge, and see if the pressures are off, and if there is a slow leak. Just a pure guess with so little info.

[Tommy Z]

Hi Glen,

Yes, I'll reach out to Charlie but always like to check here first. From Griffiths I got:
- New thermostat
- New evaporator and hurricane blower
- 2 new fender mounted condensers
- New compressor
- New receiver/dryer
- All new barrier hoses

I did not get the variable speed knob with compressor light. Had to cap myself somewhere. I suppose it could be the charge but the timing on the temp cycle is what was strange. Cruising along with 42 degree vent temps and then temps start rising to 60 and back down to 42 degrees all in about 1-1/2 to 2 minutes.

[walt]

Did you get good contact of the temperature sensor bulb and the evaporator fins when you installed this system, if not that could lead to freeze ups.

[pavegeno]

Ensure the temp probe is not near the edge of the evaporator but away from the sides. Sounds like evap freeze-up. I had the same problem initially and when I opened the evaporator, the technician had put the probe to close to the edge. I moved the probe in towards the center of the core and have been getting 29-32 vent temps for more than 12 years with a four condenser system in FL/AL summers with high humidity. My evap freezing was bad enough that I had to turn down the temp knob to warm, wait 10 minutes for the ice to melt, and then turn the temp knob cold again. Good luck.

[Tommy Z]

I sure thought I did Glen but it's on the work list to check tomorrow. My tech also thought it would be a good idea to wrap some more insulation around the expansion valve and fitting so I'll be opening the evaporator box tomorrow to check.

[Tommy Z]

Pavegeno, I hear you. I've been jealous of your consistent low temps since you mentioned them on
Rennlist! I initially thought of a frozen evaporator but the cycle happens very quickly. from 42 degrees to 60 and back down to 42 in a mater of two minutes. I'll examine the probe tomorrow and see if that makes a difference. Thanks for chiming in!

[pavegeno]

Originally Posted by Tommy Z

Pavegeno, I hear you. I've been jealous of your consistent low temps since you mentioned them on
Rennlist! I initially thought of a frozen evaporator but the cycle happens very quickly. from 42 degrees to 60 and back down to 42 in a mater of two minutes. I'll examine the probe tomorrow and see if that makes a difference. Thanks for chiming in!

Ok, mine was a slow change in temperature. Yes, that sounds like the compressor is kicking off. Good luck!

[Tommy Z]

That's why I'm thinking pressure switch. Need to figure out what's causing it to cycle like that.