2001 Dakota A/C Problem

I'm assuming that was the low side. What's the high side read? You can't make a decent diagnosis without reading pressures on both sides of the compressor.

Thanks for replying. I didn't measure the high side.I haven't ever done so,can i use the same guage I used for the low side? I don't want to blow it up or anything.

No - a high-side R134 gauge goes up to around 400psi. Typical readings are in the 250psi area. The quick-connect is a different size, to prevent you from using a low-side gauge/hose, and doing damage (mostly to the gauge, some to you).

yeah I was just reading that on a google search,i knew i remembered a red guage somewhere. Now I gotta decide do i buy a guage or take it in,where they will probably charge me just as much for diagnosis.

Is there really anything else it can be other than the compressor that breaks a lot on these damn dakotas?

Are you sure that the compressor is actually running. Is the clutch engaging when you turn it on. I have seen many people that think that just because the pulley is spinning that the compressor is turning as well when a quick look at the center of the pulley showed that the clutch was not working and nothing was moving.

Yes,the clutch is engaging and disengaging.You can hear this as well as see it with the hood open.

It doesn't sound a compressor problem. Yet.

If the clutch is cycling on-and-off then I question the accuracy of your low side pressure measurements.

First thing you need when working on an AC system is a manifold gauge set. It'll cost about $100 for a cheapo set w/hoses at an autoparts store. A shop will charge you more than that to open the hood so it's a small investment. You'll probably need a can tap and a hose for the can tap.

Eventually you'll need a vacuum pump.

If the clutch is fast cycling then what you'd probably see with a proper gauge on the low side is a starting pressure around 60PSI, then the compressor clicks on, the pressure drops to around 22PSI, and the compressor clicks off. Then the pressure rises until the compressor comes on again. Repeat.

That is an indication that the system is low on refrigerant. You don't say how long this has been a problem. It is normal for a 7 year old car to be a little low on refrigerant (some will argue). If it was serviced a year ago and now it's low then something is leaking and needs to be fixed. AC shops have sniffers and UV light setups that can diagnose a leak better than a do-it-yourselfer can. Dumping a can or two of refrigerant in every month is wasteful and irresponsible and is why we can't buy R12 anymore.

Two things to be aware of when working on AC systems:

1. After you buy the tools, your family/friends will want you to fix their air conditioners.

1. You can blow yourself up if you don't know what to do. Simply turning the wrong valve can make the refrigerant can in your hand explode. Not to mention working in close proximity to a running engine. Be careful. Do more research.

I had a '02 Dakota for several years and never had a single problem with it. It was a great truck. If it weren't for the gas mileage I'd still have it.

-rev

Thanks alot for your extensive reply.The clutch does seem to fast cycle,runs for maybe 5 seconds,stops for 10 or 15 then same thing over. I wasnt aware that it should be 60psi on the low side when it is running,I was looking atthe package of the guage i bought which said 35-45 is good,I should have consulted a dakota book.

I had a can of refrigerant I was trying to put in,but when the compressor would cycle on,the guage went up to 70-80psi which was red on the guage and I was afraid i would blow the can up,thus i figured it was full of refrigerant.

I hate to pay someone $100 to diagnose it being low on R134a.

I like the truck,but the mileage is killing me at $3.15 a gallon this week. I will try and get the guage on it again this weekend when i am off and see wht i can figure out.Thanks again!

When fully charged, the low side tends to hover around 25 PSI, but it's not as simple as just that. At idle the compressor usually runs full time.

STOP!! It sounds like you have your gauge hooked up to the high side! The fittings are different so I don't know how it could happen. When the compressor kicks on the pressure on the low side should drop. The high side pressure will increase greatly. If you plug a can into the high side, it will explode!

For $100, a shop should be able to tell you why it is low, which is more important. There are handheld devices that detect trace amounts of R134a. If the shop doesn't have one then find a shop that has the right tools.

No doubt. I had an '02 Quad Cab 5.9L and it drank fuel at 12 MPG! There's no reason for any vehicle to use that much gas. Even a full size 5.9L Ram gets better mileage. It was a great truck but I couldn't afford to drive it.

Be careful! If you're not 100% sure what you're doing then pay a shop to risk taking a face full of freon and metal shards. Years from now you don't want to explain to people that you're blind because you tried to save a few bucks on air conditioning. (You're wearing safety goggles and gloves, right?)

-rev