I figured I'd come to you guys since I'm not too familiar with the h22.

Here's what's going on:
1998 Prelude (non-SH) with an H22A4 engine. The car runs fine under normal operation, and when the engine is below operating temp, the A/C can come on and the engine will show no signs of struggling.

However, once the system reaches operating temp and the A/C is engaged again, the engine idle drops extremely low, and the compressor clutch continually cycles on and off - I'm assuming it the ecu trying to save the engine from shutting off- and sometimes will eventually die. I've been chasing the problem for about a week now, and I haven't been able to make any headway. I've pulled both the IACV and the FITV and cleaned them (backed down the plastic piece in the FITV as well), but to no avail.

I'm pretty much at my wits end with it, and it isn't throwing any codes. Also, the car recently had it's timing belt replaced (not by me) and I'm wondering if overtightening any of the belts could cause enough of a horsepower drain to kill the car when the compressor kicks on.

TIA guys, any help/suggestions are appreciated

 

i'd guess the compressor.

 

Any particular reason?


Modified by jeef84 at 3:46 PM 7/30/2007

 

apparently the bearings or the pin that is in the compressor goes out. Was or is it making any noise? If so, its the compressor.

 

Definitely not making any noises. I know they start to make some rattling like noises when they start to go, but I don't hear anything out of the ordinary. Could it be low on a charge?

Also, maybe the heat from the radiator is causing the high side pressure to go up (since the condenser is right in front of the radiator)? So maybe when the engine gets hot, it simultaneously creates more work for the compressor. Idk, I'm on brainstorming status.

 

This sounds like the ecu isn't adjusting engine mixture(and therefore idle speed) when AC load is being placed on it. The ECU does the same thing when you've increased your electricity demand at idle since the alternator starts taking up load.

When the engine is cold, it's already running rich so there isn't an rpm drop with the increased AC load.

Perhaps when the timing belt was changed, the shop knocked part of the wiring loose, specifically the "demand" signal wire to the ecu.

 

Interesting. Is that particular wire separate from the signal that the eld generates?

 

eld? huh?

 

also... clean out your throttle body and the circular piece in the center, it can cause problems if it is not clean when the engine heats up.

I recently cleaned mine and it cleaned up the idling speed.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VTECnKEN &raquo;</TD></TR><TR><TD CLASS="quote">eld? huh?</TD></TR></TABLE>

my thoughts exactly.

as a temporary fix you could up the idle slightly with the idle screw. but definitely look into either the ELD or the alternator possibly being weak.

keep in mind the timing belt is on an autotensioner so you cannot overtighten it. check the accessory belts by trying to take the belt between two fingers and turn it 90 degrees. you should be able to do that easily, if you can't they're too tight.

 

Yea we've been screwing around with the idle screw for the longest, but I honestly think there is a different problem. In all honesty, it really does seem like the ELD isn't sending a signal to the ecu to raise the idle. I'm going to see if I can check it out today.

Question though: What distinguishes a bad ELD from a weak one? Doesn't that
usually throw a code upon malfunction?

 

LoL, so what in the world is an ELD?

There should be a procedure in the Helms to see if your ECU is receiving a signal from the AC to bump up idle. It'll involve backprobing either the ecu connector or the various relays and switches that are part of the AC. The signal can come from almost any part of the AC circuit, so you'll have to look in the manual to see where it comes from on the prelude.

 

The ELD is the Electronic Load Detector.

 

the ac doesn't directly cause the car to up the idle as far as I know, I'm going to check that out in the helms in a minute though.

In hindsight, I don't think the ELD would do something like this, the AC load is on the engine, not on the electrical system.

Try this, turn the AC on but only put the blower on the lowest setting, so that the compressor actually turns on but there is very little electrical load from the blower motor.

 

If the idle still hunts with the blower on low, what should I be looking for?

 

I cannot run the AC without the idle dropping and cutting the car off most of the time. Also, at opp temp, when the cooling fan comes on, the idle will drop to 500rpms and want to cut off. Where is the ELD and how do I replace it? I have had this problem for over a year. If you combine Headlamps + AC + Cooling Fans = engine shutting off! Thanks, Wes

 

Hey thanks for the help guys. We figured it out. The fan was wired backwards, which was pushing air through the radiator and condensor instead of pulling it through. Thanks for all the help guys!

 

was the fan wired wrong from the guy who did your t-belt? my car has recently been doing the same thing, so i kinda want to find out whats wrong with it-

Thanks-

 

Yes it was. It was another tech in the shop, actually. The company we bought the fan from wrongly informed him that one fan was supposed to "push" and one fan was supposed to "pull", and he wired it up accordingly. The cooling system worked fine, but the A/C system pressures were insanely high due to the fan pushing the air through the radiator. Lame