The A/C was blowing room temp air. I seen him connect the gauge to the connector on the top, which I assume is the low pressure side? He didn't connect the high pressure side gauge. Then I saw that the low pressure was low and he said he gotta add coolant and dye to identify possible leaks. To add the coolant, I don't think i saw him connect anything else either, just that low pressure side connector. After adding coolant, the A/C was blowing real cold again, and he showed me with UV light that there were no leaks that were spotable (I removed glovebox so checked around there for leaks too).

AC worked fine after this for a month, but today after about 8 mins of use during a drive, it was barely cooler than room temp. So I'm wondering if the did something wrong.

I watched an explanation video of how AC work and it said to connect both the high pressure and low pressure gauges to better see what possible issue is.

 

Ill try to answer this as simple as I can. I do auto ac work everyday. Yes sometimes we can and do add freon at times just by hooking up the low side(suction side). No problem in doing that. However hooking up both sides allows you to see system pressures in operation. If the system is empty or perhaps the high side schrader, depending on the type may leak or has been capless and is full of crud, I wont hook to it and will charge only from the low side also. He did nothing wrong, In situations like this I have my customers return in a week or less for a recheck, that is when you typically find it, it takes some time, sometimes for it to seep enough to glow.

The OE system does not contain dye, the freon he added should, the dye is stored in the machine and it adds the correct amount. Have him recheck the system for a leak. Freon is a clear odorless gas, usually leaving only residue with small seal leaks or seeps in the hose crimps without the dye being added. Have him look at the suction line in particular but pull the cover back and look at the ends of the crimp where the rubber and metal meet, I recommend to also shine the dye light on the drain water to make sure it does not glow. That eliminates the possibility that the evap core and connections in the heater box behind the dash are not leaking, as they are hidden and cannot be seen without removal. What you describe however is Normal.

I did read in an earlier post that your ac blend door actuator does not work, If you have digital climate control, it also means you have a 10 pin blend door motor, which is not the one listed for your car. I had to buy one from an infniti j30 to fix mine in my 95 max with digital climate as it's failure to move causes the blower to only blow half speed when its not in the correct position.

I've found that in time the worm gear inside the blend door motor cracks and allows the tiny motor to free spin but not actually turn anything. I ran into this so I temp fix mine it until i could find another.. in the end I now have three. Take yours apart and see, if yours is in fact this one and you need it, lmk ill send you one of these, Keep us Posted

 

if all he did was add refrigerant and look for a leak with dye he is not a good ac tech. also not following EPA regs. illegal to charge a system with known leaks. if its low it HAS a leak.

how i do things...

recover (to know exactly how low system is)
vacuum and monitor for decay (verifies there is in fact a leak. no decay, no leak.)
charge system and monitor operating pressures
run over entire system with sniffer (this usually takes me a good 5-10 minutes. im very thorough)

if no vacuum decay and no hits from sniffer release car to customer. ive only had 1 car not pop on the sniffer that did have decay. (newer f150. was leaking through compressor shaft seal due to pressure differential in the compressor. thankfully i still have friends at ford that was able to let me know about that one)