A/C Troubleshooting

[Ernest1863]

Hi All!

Sold my 03 a few years ago but I’m back in the game fixing up a 99 sr5 v6 4x4. One of the issues I’d like to fix by summer is the A/C. The compressor clutch never clutches so I can’t add coolant and it never blows cool. The A/C button is backlit but does not light up when pressed. I’m not sure where to alligator clip to test the compressor and I don’t want to parts cannon it but it feels like I should start with the switch. Does this feel like it’s the switch to y’all or would yall more suspect a pressure sensor or relay?

 

[phattyduck]

How are the system pressures? The compressor won't engage if there is no refrigerant. If it is out, it will turn on once you start adding refrigerant... You'll want some dye to find the leak, but make sure you don't use anything with a 'stop-leak' in it.

-Charlie

 

[2TH4IST]

Exactly what phattyduck said. No freon, compressor won't turn on. 2 things to do, invest in basic ac gear, a gauge manifold, basic vacuum pump, thermometer, freon cans and ac oil.

Honestly unless your going to be doing lots of ac work it's cheaper to just take it to a ac shop and have it checked. Then diy the repair (that is if there is a freon leak).

 

[Ernest1863]

Cool, thanks both! Yea was wondering about if it’d be worth investing in the testing gear. Good thought on the diagnosis at a shop and diy repair. I’ll likely do that. Thanks again!

Edit: just for curiosity’s sake, shouldn’t the A/C light still light up or at least blink when turned on if the pressure is off and tripping a pressure sensor?

 

[phattyduck]

Cool, thanks both! Yea was wondering about if it’d be worth investing in the testing gear. Good thought on the diagnosis at a shop and diy repair. I’ll likely do that. Thanks again!

Edit: just for curiosity’s sake, shouldn’t the A/C light still light up or at least blink when turned on if the pressure is off and tripping a pressure sensor?

The AC light should come on, based on the diagrams (some older Toyotas were able to turn off or blink the AC light to show errors, so I had to check). Make sure the blower fan is running, since that must be on to run the AC.

-Charlie

 

[2TH4IST]

Also, check to see if they pulled the fuse. If they did, DO NOT put a fuse in until you check to make sure the compressor isn't seized. You can turn the clutch by hand, engine off (very front of the compressor, circled in red). If it rotates, usually a little resistance, it should be good and you can put the fuse in, of course if that's what they did.

 

[Ernest1863]

Fuse was the first thing I replaced. I’ll try turning the compressor by hand tomorrow. What happens if is seized and it runs? Trash the compressor?

The blower is working fine. Heat is great haha

 

[brillo_76]

If your compressor is seized. Replace it.. I had one start to freeze a month ago and I pulled the AC fuse until spring.

Like other stated if the coolant too low or non left the compressor will not engage.

Do you have gauges or a way to check the low side of the refrigerate to see if anything is there?

Those diy kits that have a hose with gauge would work. Just snap it onto the cold side and see if you have any psi in the system.

If zero.. You probably have a leak somewhere.

 

[96RedRunner]

Good info been passed along for troubleshooting. Local parts store rental is best route to take
for equipment to do job.
When it comes to charging system with freon 2 12oz cans or 1 24oz can puts charge weight
in the plus minus range of factory specs for charge.
And with the age of system change the filter/drier it can bite you in the azz.

 

[2TH4IST]

If the compressor is seized and the clutch engages, either the belt will snap or the pulley/clutch will snap off the compressor, which can do nasty damage.

 

[Ernest1863]

Thanks all!

Tried out the compressor clutch today and it turns pretty easily.

It may be a week or so before I can do the rental gear and do some testing. This weekend I already have the front brake pads slated (first time doing brakes) and have limited time during the week.

In the meantime I’m going to watch Chris fix’s AC recharge video I suppose.

Sounds more and more like a leak ran it dry. Would y’all try to find it yourselves or just take it to a shop if it’s got 0 pressure?

 

[phattyduck]

Sounds more and more like a leak ran it dry. Would y’all try to find it yourselves or just take it to a shop if it’s got 0 pressure?

Take a look at all the fittings (o-ring locations) and the condenser (physical damage) to see if you can spot the leak. If it is a large one, it will have oil residue in the area. Not foolproof, but it is free...

-Charlie

 

[Malcolm99]

You can jumper the 2 pin AC pressure switch by the firewall passenger side to test compressor clutch, Receiver drier must be replaced when empty or opened to atmosphere for any length of time, usual cause of leak is the evaporator under the dash so you will also need a expansion valve if that is the case, the FSM has the volume of PAG oil that is to be added to each component replaced. I've had to do this job twice now on both my 97 and 99, it is DIY, evaporator comes out easily from under dash, if it is the condenser you are laughing, but you'll still need receiver drier and to vacuum the system down to boil/remove the water from the system and a gauge set. A O-ring and schrader valve kit is handy to have in stock aswell.

 

[Ernest1863]

Hi all

Just wanted to update here. Got it vacuumed and recharged, tested everything, compressor works but never got power, replaced the amplifier/relay, nothing.

Got an $8 replacement A/C switch in today and turns out that was the only thing wrong the whole time.

Learned a lot though. Thanks all for the suggestions!

 

[nissanh]

Nice.. but first check would be power and ground to any electrically controlled device. My cousin runs a sienna Uber in NYC and the AC went out. I gave him step by step instructions but he failed to follow and bought a used Toyota compressor, vacuumed and recharged and it turned out to be a faulty clutch pack.

What's strange to me is it is a 2018 Sienna 200K miles.. while non of my older Toyota's 92, 97, 2000 have shown any sign of bad ac.. Guess newer toyota's are not so reliable!

 

[Ernest1863]

Yea I’m a noob still when it comes to electronics diagnostics. I can work a multimeter but wasn’t sure where to put the leads to test the switch socket or compressor for that matter.

I will say, the system was a pound low so the refill was at least needed.