Engine running rough when Air is on

[DonM]

Ok this has been an on going problem for a while now. I think im getting closer to finding the problem?

I noticed when i have either AC/heater, or defrost. The engine runs rough and the whole vehicle vibrates. The tail pipe rattles and vibrates the most. The muffler and pipes were just replaced not to long ago. Even before the new muffler and pipes it all ways did this!

Im not sure how to explain this, but here goes. When i turn the heater on, i here a clicking noise coming from under the hood. I guess this is the engine going thru cycles? When this happens i notice a small power like surge and then the vibrating starts. When the cycle is over, the vibrating stops! This is while in drive but at a stand still, if i were to put it in "park" the vibrating would stop.

I was waiting in line at the car wash today and it has been bothering me. So id like to finally get to the bottom of this.


Thanks

Don

 

[VOATMJ1]

Sounds like your compressor is kicking on, (which it should) in the A/C and Defrost mode. It should not be coming on in the "Heat" mode however.

The surge you feel is probably a sensor (IAC-?) not responding to kick up the idle speed, when the compressor comes on, which might cause the vehicle to shake because of the lower idle speed. Anyone else?

 

[DonM]

I forgot to mention, in the last years ive had two Iac and PCV replaced. So it cant be that.

Im trying to remember what else has been done that may also cause this problem. I think that is all?

VOATMJ1, so what im feeling is normal then? Thanks


Don

 

[VOATMJ1]

No, what you are feeling is not normal. Do you have any vacume leaks that may show up a lower idle or under load when sitting still?

 

[DonM]

Ive looked for vaccum leaks before, i never found any.

Also, i was under the hood the other day while the defrost was on, i noticed the compresser, (i think it's the compresser?) The pully turns all the time, but when it goes into cycles the plate on the front of the pulley stops and moves slowly, but then starts spinning again.

Ive never noticed this before and thought that might just be the problem?


Don

 

[DonM]

Any more responses?

 

[Nate1]

Sounds like what you are seeing is the A/C clutch... does it cycle on and off when the ac controls are set to panel? It usually lets a little clink out when it drops in, but it sounds normal. I'm not sure whats wrong with your engine...
-----Nate

 

[DonM]

Yeah i hear a little clink type of noise. Ok so that is normal? But what about the vibrating when it goes into cycle???


Don

 

[TPLYNCH]

when your compressor kicks in, your rmp's should increase slightly to counter the demand. This is done by the IAC. That's normal. The roughness may be either the IAC isn;t working properly, or your compressor is causing more drag than it should. If your IAC is new, then I would guess your compressor may be going. Also, check any vacuum lines/connectors and make sure there are no leaks.

 

[DonM]

Yeah, all obvious has been checked. I checked all vac lines my self twice and had a local shop check also.

I mentioned this above, the pulley on the Compressor turns all the time, but the plate on front of the pulley stops and turns slowly for a few sec, then it turns with the pulley at normal speed. I think what im looking at is the Compressor?

Thanks for the help


Don

 

[TPLYNCH]

That's the units clutch I believe.

 

[kps36]

What you are describing is exactly what was happening on mine about 2 years ago. In defrost mode (A/C cycles in that mode also) it started 'shuttering' until I turned it off (A/C stopped cycling). Hmm..About 2 weeks later the AC Compressor completely seized up and black powdercoated the engine bay (clutch material) and it has been short belted since (bypassing the A/C).
It is not to be ignored.

 

[DonM]

So how much is a new Compressor gonna cost?

 

[DonM]

Ok, the compressor turns on and off every couple of min. I didnt actually time it, but it's about 2-3. The clicking type noise i here is the Compressor turning on and off, right?

Can someone please help me out here?


Don

 

[bluevolume]

The compressor kicking on and off is normal - that is why your vehicle gets cool but doesn't freeze inside. The effects you are seeing when the compressor is engaged could be a few different problems:

Your system could be over-pressurized. If the system was serviced and was accidentally overfilled, that will make the compressor work harder, and could cause the engine to shake.

The compressor is starting to go. Eventually, all A/C compressors will fail, their life usually directly related to how often you use the A/C. Once it starts to fail, it will get more and more difficult to turn, causing your engine to work harder just like above.

If the A/C system is fine, then it is possible that the engine is not properly throttling when the compressor kicks on. When in park and idling, watch the RPM gauge when it kicks on, the needle shouldn't move much. If you are getting below 500 that is a problem.

For your question about replacing the compressor, it isn't easy to say how much it will cost. The compressor itself is around $200, but in replacing it you will have to evacuate the system then refill it with coolant. I didn't look at what year your explorer is, just hope it is new enough to not have R12 (freon). A refill with freon could cost $1000.

If you do replace the compressor, take the time to disassemble the old one and look at how they work. There are some pretty unique and interresting ideas going on in there.

 

[DonM]

Alright, next time i go for an oil change, I'll have the tech check it out. I another search on the Compressor, I did find more info this time around, just had to dig further.

The A/C seems to work fine, could be a little colder? But it doesnt seem like a problem. I did notice the coolant level is a bit high though.

On a related note, im also having a problem with a loud squeal coming from under the hood. If there is a problem with the Compressor? I willing to bet the squealing is coming from the Compressor pulley? If it's safe, I may just spray the pulley with WD-40.

Engine idles between, 900-1000. This Is normal I believe?


Thanks for you help


Don

 

[bluevolume]

Originally posted by DonM
Alright, next time i go for an oil change, I'll have the tech check it out. I another search on the Compressor, I did find more info this time around, just had to dig further.

The A/C seems to work fine, could be a little colder? But it doesnt seem like a problem. I did notice the coolant level is a bit high though.

On a related note, im also having a problem with a loud squeal coming from under the hood. If there is a problem with the Compressor? I willing to bet the squealing is coming from the Compressor pulley? If it's safe, I may just spray the pulley with WD-40.

Engine idles between, 900-1000. This Is normal I believe?


Thanks for you help


Don

With the coolant, I wasn't referring to the radiator coolant. I was talking about the gas that the A/C system is charged with, the only way to check that is with some refigeration gauges. -- Don't try if you don't know how.

If the compressor is squeeling, you need to see what is going on -- hood open, A/C on. If it squeels with the compressor disengaged, the clutch plate could be bent or some debris could have got in there. The clutch is very simple in how it works and shouldn't be hard to fix.

If it squeels with the compressor engaged, we know the compressor is going. Turn the engine off, then remove the electrical plug from the top of the clutch. This will prevent it from engaging until you can get it repaired. ***This is very important -- if your compressor is failing it WILL eventually seize and if you don't hear it in time you'll throw the belt. Not something you want to happen away from home.

Good luck,
Blue

 

[DonM]

Funny thing is, squealing is only heard when I accelerate. No other time. I tried to get the damn thing to squeal while the engine was on and in park. Nadda.

I'll inspect everything myself, if i cant find anything, I'll just take it to the shop.

Thanks again


Don