Help with the A/C on a Honda/Isuzu
 

My girlfriend's 2002 Honda Passport (really an Isuzu Rodeo) is not blowing cold air anymore. It will get cool when moving, but as soon as you stop a light, it is no longer cool. I first thought a slight leak since it has almost 100,000 miles. I have a low pressure gauge, so I bought a can of R-134a to fill it up. When I hooked up the gauge with the engine running and the AC on max, the pressure was showing too high. It reads between 55-65 psi. If my chart is right, it should be in the 30-40psi range. Now I'm thinking that the compressor is bad. I am planning on getting a high pressure gauge to test the high pressure side.

What should I be looking for to tell me that the compressor is bad?

Is replacing the compressor a DIY job? What tools would I need? I assume a set of gauges, vacuum pump (can you rent these?), R134a and oil.

If U got 100000 miles on then you better just sell it because Rodeos and Axiums from those years have a 3.5 which is a isuzu engine (not GM) and has a faulty design...they all get knocking rods and replacement engines are not around. Go to a Chrysler dealer they got killa deals on new Jeeps with 0% notes!

Can you hear the compressor cycling as you turn the A/C on and off?


My Mom's Hyundai is having the same problems and the mechanic diagnosed it as a bad compressor just today.

I found the same readings with my guages when checking her car out last weekend. The PSI should have been around 30-40 but was closer to 55-60.

The compressor was not engaging at all.

Don't you have a club to be hanging at right about now?:rolleyes:

Speedy-ignore this nonsense advice from "Playa"

Yes, the compressor is cycling. Actually it's quite loud when it is on, which is one reason I am thinking it is bad. It almost sounds like a squealing sound. The compressor is definitely coming on though because I can see the pressure drop when it cycles. It just doesn't drop enough.

Everywhere I look, it's around $350 for a reman'd compressor. I am hoping I can DIY because I don't want to drop much $ into this thing since we'll be getting rid of it soon.

Wouldn't you know it, the warranty just ran out on this thing about 1 month ago too.

Is the fan on the condensor running?

My Mom's made a grinding sound which was apparently it slowy chewing itself to bits.


EDIT:: have you checked the belt to see if it is simply slipping or the tensioner is bad?

Our BMW tensioners would squeal occasionally which is an indication that they need replacement. Not saying it is but it is worth checking out.

She was quoted about $250.00 for the entire job so I told her to get it done. She plans to sell the car or trade it in soon. She just wants something newer/different.

I would suggest that you can do it yourself although the only problem i see is that you have to evacuate the charge. That COULD be done by simply letting it bleed out on it's own or you can buy the evac system and do it the eco-friendly way.

Once the compressor is installed you can then recharge the system with the over the counter cans that have the oil in them. It sounds like you are familiar with this already.

Are those pressures at idle or higher rpms? You won't see 35 psi unless you have more rpms. You need high side pressures to know the story.

You could DIY the compressor, but you definitely need a vacuum pump to pull a vacuum on the system. The proper DIY way is have a shop evacuate your charge. Then, you can replace the compressor. Last, pull a vacuum to remove air and water and ensure no leaks. Then, you are ready to charge the system.

You'll also want to change the drier/accumulator.

with those pressures it sounds like blockage in the orifice tube. The problem with that theory is where did the blockage come from? Normally its metal from the compressor internals failing.

If you find that the compressor has blown chunks as a few have said, I can get you a new compressor. It's not reman, and it's not OEM, but I have not had a problem with any, and I don't want your core. Let me know.

Your getting good advice thus far. Get us some high side readings but check the belt tension first.

We have a winner. It is probably this plus it is low on freon

It's very difficult to mistake a condenser fan for a noisy compressor, but Honda's are know for bad condenser fan relays. I'm going to guess the compressor is blowing metal through the system and clogging the expansion valve or orifice tube, which ever it has, just as Scott R has pointed out. This would be one reason why the low side won't come down, the other would be that the compressor doesn't suck as it should anymore. We need to see the high side pressure though, which is the only thing the condenser fan helps. It lowers the temp of the freon thus lowers the pressure.

If the compressor is making noise, it's either the clutch, the belt or the internals. You can try to add the can that you have, but I doubt it sucks it in.

If the orifice tube is clogged, the high side will go through the roof, and since the volume of refrigerant on the low side will be decreased, the low side pressure will drop, often into vacuum, instead of rise with more RPMs. Diagnosed it, verified it, and fixed it too many times.

If the condensor isn't shedding the heat (either no air flow, or semi-clogged internal passages) all of the pressures will be higher. More heat = more pressure. If the evaporator side is still trying to pick up heat, and the consor side can't get rid of it, system wide pressures will be higher.

If there is good airflow over the condensor, I'm guessing the valves on the low side of the compressor are shot.

Shoot the condensor with the garden hose, and see if it gets colder inside. When you are moving, the condensor gets more airflow, and it starts cooling again.

Agree with lm6y. A clogged orifice or sticking expansion valve will cause low side pressures to drop. Without more data, this is just stabbing in the dark.

He's right, and I've seen both an expansion valve stick open and a blown out orifice tube (my mistake, it wasn't clogged) equalize the pressure. It's not common, but it does happen. We don't know with out the high side pressure reading.

Thanks for all the advice so far.

Condenser fan is definitely running. I can hear and see it come one with the compressor.

My next step is to locate a high pressure gauge before I go any farther to verify the pressure differential.

How would I determine if the expansion valve is bad and where is this located in the system?

That's where your pressures come into play. Low side readings are pretty much useless with out the high side readings to compare them with, and vice - versa.

Just by the low side readings, the evap core could have poor airflow too, but I doubt that's it.

Get a set of gauges on there, post the pressures, RPMs, and temps. We'll be able to zero in on it then for ya.