My A/C has been making this loud clunking noise when I first turn it on. It doesn't make anymore noise when it is running. This is usually when it really hot (98,99 101 etc.) outside and it's been sitting for 8 or 10 hours. Anyways, now it seems like it takes quite a while to get cold. It's been 100+ every day here for almost a week.

I'm just wondering if I should have it recharged or topped off or what. Does the refrigerant only have a certain lifespan? Any help would be appreciated. My brother does HVAC stuff for a living and he has all the guages and the license to buy the R whatever it is.

 

The only way I know something is wrong is performance like you say. Then I get the truck up to operating temp, open all doors, crank the A/C as cold and fan on highest. Then I go check the 2 pipes going into the evaporator from the firewall, if they are both cold, one a slight bit more than the other (the larger tube I think has to be) then it's charged. If one is frigid and the other room temp let's say, it needs a recharge. In any case, it's usually mandatory to charge $$$ for a proper inspection then whatever on top of that. If your only down less than a pound, I wouldn't worry too much. Also, your compressor will cycle on and off for 5 or so seconds each, whereas it should run pretty much constant.

 

Only AFTER repairing any leak that let out the previous charge.

Just because it's legal in the states to purchase R134a doesn't mean that it's a DIY project for someone who doesn't know how to evaluate the system and make the correct determination.

Think of it this way, just because I have a pencil, would it be a good idea for me to design a highway or intersection?

Steve

 

Hmm I didn't know DIY was a licensed proffessional with an associates degree in heating and air who does commercial refrigeration for Johnson Controls.

I find it hard to believe that the refrigerant lasts forever even if the system doesn't have a leak.

The A/C worked fine this morning when it was 81 F outside. It didn't cool worth a dang for the 4 mile drive home when it was 104 F.

Does that mean my A/C has a problem or it just takes longer to cool when it's that hot outside?

Here's another thought, my evaporator might have some blockage in it. I should check it out for bent fins and stuff stuck in it. Anybody have any suggestions as how to clean it? Compressed air?

 

Im an hvac mechanic, and believe me, if there's no leak, then there is no reason to recharge. If the system was charged properly(evacuated) and it is tight(no leaks) then the gas will be good for as long as there are no leaks, or a compressor burn out.

Checking the evap coil for cleanliness is a good idea....I dont work on cars though, so can't give any advise there. Compressed air is fine, just try not to bend the fins, or use a nylon brissled brush.

If its 100 out, its going to take a while to get good and cold. Everything in your truck is roasting and has to have the head pulled out.

Dont add any freon unless you're sure its low. Have your bro put some gauges on it and check it out if he has the adapters.

 

Thanks Triton, that makes sense.

I checked the temp. of the air coming out of the vents when I got home today. It was 105 outside. Idling in park the temp was 68 coming out of the vents. Once I started going down the road it dropped all the way to 57.

Over at flatratetech some of the guys were saying the vent temp should be independent of the outside temperature. Another guy said a 40 degree difference is good. That's a 40-50 degree drop, so I'm guessing that's good.

 

sounds like you answered your own question.