I have a 2000 Dodge Caravan with a 2.4L engine. I know that this is engine is naturally weak; it's small I get it. The engine runs great and smooth and all. However, when you turn the ac on, acceleration is a drag. It's ok in 1st gear but when it changes to second it doesn't do much, it just gradually and slowly gains speed. You can tell a difference when it kicks off it is an immediate power gain until the compressor kicks on again.
I had a friend tell me to get the coolant system flushed [it is NOT overheating so no problem there] and it would give the engine more power while the air is on. The engine to our knowledge has never had its cooling system flushed. It has 211K on it and not using excessive antifreeze or anything. It is green and remains full.
Is this true? Are there any other ways or checkpoints or tweaks to give the engine a little more power while the air is on?

Thanks!

 

How long has this been going on? I will assume the 221k is the mileage and it is in mileage. Meaning 211,000 miles, is this right?

If this is true, I would do the coolant flush but for maintenance purposes only, it won't help with the AC and the power loss. What the problem most likely is that the AC clutch is getting ready to seize up. There are 2 parts to the main AC. The clutch and the compressor. The clutch is the part that the belt actually wraps around. When the AC activates, you may hear a loud click. That is the clutch engaging onto the compressor. When not on, the clutch spins freely with little stress to the belt system. Activated, it does add stress to the system.

Also, with that mileage, when was the last tune up done. Meaning plugs, wires, oil changes, transmission, battery replaced, etc? All of this can play into a power loss. High mileage cars without tune up will lose power across the board because plugs and wires aren't sparking and conducting like they should, alternator/battery might not be putting out the proper amps for optimal performance just for example.

Everything that I listed here is fairly cheap to take care of yourself if you are handy. If not, maybe a friend can help. If maintenance was done properly, I would go back to looking at the AC clutch.

 

Like L and R two was asking, did this problem just started or has it been doing this for sometime? I know you have a 2.4L engine, but what transmission do you have? If its the 31TH(3speed) you may need to have it serviced and adjust the bands.

 

yea it has a good tune up on it pretty much. and yes it is 211,000 miles. the plugs and wires are all fairly new i change the oil religiously. to be exact, i just re-adjusted the gap on all the plugs last week.
the transmission i have done nothing with... should i have the fluid changed or flushed or adjustments...? whats the regular maintenance with that? it doesn't slip or anything it's a good transmission good car.
also, it has always been somewhat weak with the ac on. my dad has recently replaced the timing tensioner (as you may have seen my inquiry thread earlier) but it's back in time runnin smoothly so i wouldnt think that would have affected it. it just seems quite a bit weaker to me this year when the ac is on than in the past.
however, i will say this. it has done this weird thing for a long time so i never really put much thought into it BUT when the air is running and you're driving down the road at one speed, it's like it will stop pulling for just a quick second hardly enough to worry about. the speed doesn't change but you can definitely feel it stop pulling for a quick second. its hard to notice but im very in tune with my vehicle so i noticed.
my main concern is just getting some more take-off when the air is on because it's like grandma. it still moves and all but second gear especially just very laggy on the acceleration.

 

I have never driven a caravan, so I am not sure if they are sluggish alot with the ac on or not, but some of the smaller engined cars no matter what it is will be more sluggish with it on.

When you feel that slight nonpower thing that you were talking about while driving is definitely the clutch engaging. All cars do it, but like I said, in the smaller lower power engines is where people will notice it more. Takes the car a fraction of a second to adjust to the change, but it is noticeable to those that pay attention to their car.

The only thing that I can suggest to try would be to have the AC clutch changed. It is fairly cheap and easy job so if it doesn't improve, it is not a total loss. Or you could just leave it as is.

Now as far as the tranny goes. With 211k miles and not knowing when, if at all, a good service has been done to it leaves me a little in awe. This is a good awe too since there is 211k miles and never has really been serviced.

With that mileage you will get mixed comments here. Some will say don't touch it and give all the physic reasons why. Most dealerships and shops won't do anything over 150k miles anyway and some won't touch it over the 80k mile mark. Some will tell you to do a full service change and flush and give you reasons.

IMO, I wouldn't do anything other than make sure that the levels are good.

 

alright well thank you for everything.
but as far as the transmission is its fine doesnt slip or anything but i will check the fluid.. it has to be running and in neutral right?

 

compressor agreed

it should be a little more sluggish with ac on but not that bad - your compressor is probably getting sticky - might want to do an oil charge to your ac system - that may help and add some life to the compressor

 

I want to try replacing the A/C clutch. How much am I looking at? I'm sure I can do it myself..how do you go about doing it? Just take off the belt and somehow pull the clutch out of the compressor??
@battleaxe: how do I do an oil charge to the system and how much does it cost?

 

the clutch is NOT your issue. the clutch only transfers belt movement into the compressor. you 'could' be having a compressor starting to fail, however a trained A/C person would need to see/feel the resistance in the compressor to truly determine if that is indeed the issue you are having