4runner makes tapping noise when heat/ac is engaged?

[cHRiSCOe]

So I've been warming my 4runner up in the morning here lately. The other morning i went out and cranked it up went back in side for about 5 minutes and when i came back out it was making some very loud noise. As i walked toward it, it sounded like whatever was making the noise cut off and the noise vanished. My only idea is it has to be something to do with my ac/heat cause it only does it when one or the other is blowing. The sound is like something tapping. I does not do it everytime the heat is on just sometimes. If i cut the heat off it will quit.

[Seanz0rz]

well, describe the noise for us. a banging noise, squeeling, woosh, ka-chung ka-chung ka-chung, kitty sleeping on the fan belt noise?

also, details about your 4runner.

[cHRiSCOe]

1998 SR5. the noise is hard to describe but it sounds like it's coming from somewhere on the intake side. Also I was just sitting in the drive through and it started doing it. Heat was NOT on this time!

[cHRiSCOe]

1998 SR5. the noise is hard to describe but it sounds like it's coming from somewhere on the intake side. Also I was just sitting in the drive through and it started doing it. Heat was NOT on this time!


Ok so i thought of what it sounds like and it happens only while the heat is on. It's like a tapping/ knocking sound, and the taps speed up when you give it gas. Hopefully my only vehicle is not about to kick the bucket!

[DHC6twinotter]

What position is your hvac dial set at? Is it on defrost when it makes the noise?

Have you tried turning on the AC? What happens if you turn on the AC?


Also, can you varify whether or not your problem happens when your heat is on? Your last two posts say different things. :D

[Seanz0rz]

could be something to do with your AC system. either when the clutch is engaged or disengaged.

try doing this a few different times (over the next few days if necessary):

heat on, AC on (mixer all the way hot)
heat on, AC off
heat off, ac on (mixer all the way cold)
heat off, ac off (just the fan running)

and report back with the symptoms.

[DHC6twinotter]

could be something to do with your AC system. either when the clutch is engaged or disengaged.

Exactly what I'm thinking.

[4x4mike]

How cold is it where you're at? Fan clutch going out?

Once you 4Runner warms up and you've driven it some what RPM is your idle?

[cHRiSCOe]

Yeah sorry about that. It only does this when the AC/Heat is ON. The bad thing about it is it does not do it all the time. It may start as soon as I cut my vehicle on, or it may just randomly start going down the road. So if I go to a garage to get it looked at my luck it wouldn't even do it for them to hear.

As of whe I live at. North Carolina, so it's not very cold. Maybe upper 40s the lowest it's got so far.

I did have a problem with my heat not being very hot but i was looking at forums here and at yotatech and what had happened is my switch is messed up and the white control arm down on the passenger side was not being moved by it.

[4x4mike]

I'm thinking it's the compressor. The compressor itself could be going out, the clutch or maybe just the bearing. It could also be a loose belt slipping when the compressor turns on.

A little more help on what it actually sounds like might help more.