A/C troubleshooting

Anyone got some experience troubleshooting A/C issues? The truck blows air but its not cold. Its just whatever temperature it is outside. When I press the AC button it makes a slight hum sound, when i press the cycle air button on the dash it hums much louder. Im suspecting its out of coolant and possibly the fan is loose or something. Anyone had this issue before and fixed it? I made a video, sounds kinda like an engine, but its not, that's the ac. At the end of the video i turn the ac off and the sound goes away.

https://drive.google.com/file/d/1SQR71V4N_rmtrnroxWpLxnvXjVrZ9xix/view?usp=sharing

Im thinking about recharging the system with the UV dye leak detector stuff. As far as the hum goes, is it as simple as a bad fan? I was trying to find the cabin air filter but I guess 1st gens dont have them.

 

Your are on the right track, probably low on fluid as you said. Check for leaks as stated.
I had the clutch pop off the compressor once. I was testing around and couldn't figure it out. Had to do a oil change any way so when I pulled the skid pan the clutch and shim were just chilling on the pan. Crazy cuz we did a long dirt road and road trip home and it didn't fall out. Just bolted back on and it's been good to go.

 

check the tension on the belt. I recently had something similar to this happen to my inlaws tacoma 4 cyl. I would turn on the AC and it really wouldnt blow cold air and it was noisey. Drove it like that for a few weeks till finially i got a chance to check things out. The belt was loose. Tiighten it up and now it blows cold air and noise gone. Good luck

 

You're on the right track. Any time you are diagnosing an A/C issue my best advice is to put a set of gauges on it first. Not those little chinsy ones that come on the cans - a full set that show the high side & low side pressures.

If your low side is below 20 PSI - your compressor should not kick on as the low pressure switch cuts power to it. If you have little freon in there I would get some with a dye and charge it to about 25-30 PSI. If there is NO freon in the system and you suspect that it has leaked out - do yourself a favor and rent a vacuum pump from Autozone, put a vacuum on the system and then let it sit for about an hour. If you've lost vacuum you can confirm there is a leak.

If your high side exceeds 275 PSI than that confirms you either have a blockage somewhere or your expansion valve has failed. Normal operation should be around 150-250 PSI.

Last but not least a few other things to check out include your compressor's clutch & your low pressure switch. Always check for the simple stuff like belts & Idler pulleys.

Any time you open your A/C system, whether it be to replace o-rings or replace a component always replace your expansion valve & drier and flush out all of the lines.

Hope this helps!

 

So i want my low side to be above 20 psi but below 30?

Do you think the harbor freight pressure gauges are decent enough for the job?

Lastly, what would cause that humming noise coming from the glovebox? Is that a fan or the condenser that is going bad?

 

might be just a dirty blower motor. easy to replace

 

The humming noise coming from the glovebox area is probably the blend door actuator. Mine is what I would call more of a buzzing sound, kinda rhythmic. Only happens once in awhile. Turning the climate control dial from cold to hot several times quickly sometimes makes it go away for a bit.

 

Was the tension belt easy to access and tighten?

 

I think it was. You gotta get under the truck. You might be able to do it from on top. I believe you gotta untightened a bolt on the pump and then tighten the bolt on the tensioner till you get the desired tension on the belt

 

Yeah, if you're concerned there is a leak save the money on Freon and charge it to right around 25. Check it with gauges every weekend and see if pressures have dropped at all.Harbor freight special should definitely do the trick or you can rent a set from an auto parts store.

Belt tensioner is super easy to get to - pop off your skid plate and look underneath the truck right at the compressor. To the right of the compressor you'll see a bolt at a 45 near the idler pulley - should be a 14mm. Loosen that and then loosen the nut on the idler pulley itself and you can take the belt off. If you want to tighten it, loosen the nut on the idler pulley first and then tighten the other 14mm. Tighten the other nut when you're done.

 

TY! Looks like I got some more work this weekend.

 

Ok so I replaced the blower motor and that fixed the humming sound. Now I have a whisping or slight grinding sound when I engage the ac button. I'm assuming that is the evaporator. I will inspect the pulley for it tomorrow and also pull a vacuum on the system. I suspect the evaporator might be bad

 

So I did some more troubleshooting;
1. Took off the skid pan and checked out the compressor. Belt didn't seem too loose.

2. Hooked up the ac gauges. Here are the pressure before starting ac and after. Are these readings indicative of anything more than just empty refrigerant?
Before
After


3. Turned on the car with ac full blast for 5 mins. Didn't hear anything coming from the compressor.

4. Went to check inside the cabin. Sound is definitely coming from inside where the evaporator/ac blower is. Next step is to open it up and and see under the dash.

 

Not a HVAC tech but it looks like either you don't have enough freon or the compressor isn't working or clicking on.

 

Ok another update. So I opened up the evaporator under the glove box and man it was dirty.




I cleaned it out and put everything back together


However I still get the hissing sound coming from the evaporator... Here is a link to a video where you can hear it when I start up the AC and then hear it when I turn it off. Is the evaporator going bad or is this normal? My other Tacoma doesn't make this sound.

https://drive.google.com/file/d/1VESAwrhypyL5C1px3ZR5FW1sVvyGla_f/view?usp=sharing

Lastly after cleaning the pressure on low side when back up to 0 and high side went up to 75

 

Compressor is working or the pressures would not have changed. Your low side is actually drawing a vacuum and the high side is low so I suspect you’re low on charge. Here’s a guide for charging.

 

BTW the part you’re showing is the evaporator, the condenser is in front of the radiator.

 

Oops I will go back and change the posts to reference the evaporator. Thanks!

Do you have any idea why the evaporator would be making a hissing sound in the video? Is it a bad bearing inside? Its only noticeable on low and semi low settings on the AC. Semi high and high the fan over powers it.

 

time to pull a vacuum and see if we have any leaks!

 

The hissing typically is the refrigerant flowing through the expansion valve, when the system is low on charge you start getting vapor going through the valve instead of liquid refrigerant which will make the hissing more noticable. If you still hear hissing after the truck has been off several minutes your hearing a leak.

Compressor will tend to be more noisy too on a system with low charge because the refrigerant carries the oil with it and a system low on charge since theres not enough refrigerant to carry the oil back to the compressor it won't keep enough oil in it and it will get noisy and eventually cause damage.