The "quickly ending" A/C fuse

[T4RunnerSteve]

Fellow 3rd Geners -- my son & I are having a problem with his 2000 T4R & the A/C -- here is what we're experiencing:

- A/C worked great last year. I'd replaced the whole system only 2 years ago -- compressor, condenser, drier, etc. w/ OEM parts

- the A/C button broke so after "paperclipping" it for about a year, I got a used OEM one off eBay. Oddly this new one would never turn off but at least the A/C was nice & cold

- this year, if we turn on the A/C, the button lights up & after a little bit of ice cold air, the 10A fuse under the hood blows. Change the fuse... A/C works again... blows

- my thought is a defective button. I get a brand new OEM A/C button this time & while it functions properly (turns on & off when you push it), the fuse still blows after a short time

We searched these forums & see everything from a bad A/C clutch to a bad alternator being suspects. Is there a way to test these two parts manually? Would be good to be sure what's wrong before buying parts. Also, any other ideas? It feels like the compressor *should* be fine since it's OEM Denso & so new...

Thanks in advance!
-Steve

 

[Ralph Blake]

First off who ever told you to change forums gave the wrong directions because it’s an air conditioner problem same whatever forum you asking a question about.
Now the fuse problem there is something drawing to many amps compressor or fan these are the components I would check as to their current draw amount.

 

[phattyduck]

This advice is only for the "manual AC" '96-'00 trucks.

You can 'test' the switch pretty easily by using a defrost mode (either of the two), which turns on the AC (check for temperature - the button light will not turn on). If that does NOT blow the fuse, then somehow the switch is the issue.

I would suspect the compressor clutch though - the spec for the AC clutch is 3.7 ohms (approximately), which would draw less than 4A. Check that with a multimeter. You can also unplug that connector and see if the fuse blows (obviously, AC won't work...)

The AC fuse also powers the AC amplifier, AC switch and that's about it...

-Charlie

 

[AuSeeker]

First off who ever told you to change forums gave the wrong directions because it’s an air conditioner problem same whatever forum you asking a question about.
Now the fuse problem there is something drawing to many amps compressor or fan these are the components I would check as to their current draw amount.

I saw his post in the 4th Gen section, I didn't tell him "to change forums", I simply told him the following.....

"You have posted this in the 4th Gen section, you may have better luck posting in the 3rd Gen section."

I posted that so he would be posting in both sections and more than likely get more views and replies, especially from 3rd Gen owners who may have had the same issue that might not be occurring on 4th Gens.

 

[weberlukas74]

Fellow 3rd Geners -- my son & I are having a problem with his 2000 T4R & the A/C -- here is what we're experiencing:

- A/C worked great last year. I'd replaced the whole system only 2 years ago -- compressor, condenser, drier, etc. w/ OEM parts

- the A/C button broke so after "paperclipping" it for about a year, I got a used OEM one off eBay. Oddly this new one would never turn off but at least the A/C was nice & cold

- this year, if we turn on the A/C, the button lights up & after a little bit of ice cold air, the 10A fuse under the hood blows. Change the fuse... A/C works again... blows

- my thought is a defective button. I get a brand new OEM A/C button this time & while it functions properly (turns on & off when you push it), the fuse still blows after a short time

We searched these forums & see everything from a bad A/C clutch to a bad alternator being suspects. Is there a way to test these two parts manually? Would be good to be sure what's wrong before buying parts. Also, any other ideas? It feels like the compressor *should* be fine since it's OEM Denso & so new...

Thanks in advance!
-Steve

To test the A/C clutch, use a multimeter to check its resistance, which should be within the range specified for your vehicle. For the alternator, ensure it is properly charging the battery by testing the voltage across the battery terminals while the engine is running.

Also, check the A/C clutch relay, as a faulty relay can cause issues with the A/C system. Inspect the A/C compressor clutch coil too, as it can wear out or develop a short circuit over time. Use a multimeter to test its resistance and ensure it matches the manufacturer's specifications.

Additionally, even though the A/C compressor is new, there could still be internal problems causing excessive current draw, which might blow the fuse.

 

[T4RunnerSteve]

This advice is only for the "manual AC" '96-'00 trucks.

You can 'test' the switch pretty easily by using a defrost mode (either of the two), which turns on the AC (check for temperature - the button light will not turn on). If that does NOT blow the fuse, then somehow the switch is the issue.

I would suspect the compressor clutch though - the spec for the AC clutch is 3.7 ohms (approximately), which would draw less than 4A. Check that with a multimeter. You can also unplug that connector and see if the fuse blows (obviously, AC won't work...)

The AC fuse also powers the AC amplifier, AC switch and that's about it...

-Charlie

To test the A/C clutch, use a multimeter to check its resistance, which should be within the range specified for your vehicle. For the alternator, ensure it is properly charging the battery by testing the voltage across the battery terminals while the engine is running.

Also, check the A/C clutch relay, as a faulty relay can cause issues with the A/C system. Inspect the A/C compressor clutch coil too, as it can wear out or develop a short circuit over time. Use a multimeter to test its resistance and ensure it matches the manufacturer's specifications.

Additionally, even though the A/C compressor is new, there could still be internal problems causing excessive current draw, which might blow the fuse.

Thanks all! Your tips led me to the A/C clutch and as I was following that wire, I found the problem: a cut / frayed wire that was shorting out against the outside of the compressor itself. Picture attached. After pulling it away from the compressor, the A/C doesn't blow fuses & cools nicely.

I'm going to cut & slice it properly to hopefully keep it cooling into the sunset. Thank you for this great resource: saved me a lot of money in wasted diagnosis fees & parts! Have a great Summer!