oliversok

Hi everyone,

I have been having issues with my a/c not engaging and when it does it would disengage randomly, usually when I give it some gas; odd thing is that when it is relatively cool outside the compressor seems to engage a lot better, but when its get hot out like today (105 degrees F) the compressor has a very hard time engaging. I changed the compressor with a brand new one and had it charged and confirmed that there were no leaks.

My diagnosis of the issue:

I recently got a K24 swap done at a shop and the shop mounted the a/c compressor right underneath the header. I think that the excessive heat from the header and weather is affecting the a/c thermal protector and causing the compressor to shut off?

I spent so much time and money trying to figure this issue out.

Any experiences or help would be appreciated

- Thanks

Pics for reference: Does anyone see any potential issues with this setup?

Iyan112

Couple things you can check. Ac relay itself, possible as it heats up, it can start failing making the coil not energizing. These are specs off a 04 compressor. Check the air gap between the clutch and pulley with a feeler gauge, the larger the gap, the more distance the coil has to pull the clutch to engage it. Also measure the resistance of the coil. Higher the resistance, the weaker the field of the coil to magnetize the clutch to engauge it.
i made a test switch for work where I can remove the ac relay and plug in a momentary sw using the relay power pin and field coil pin. When I press the button, it will energize the coil and you can physically see if the clutch engauges when the button is pressed.

Car Analogy

What is the belt routing?

The tensioner must always be after all driven pulleys. Otherwise there won't be belt tension to drive that component.

Its OK to have idler pulley(s) after tensioner, but not driven pulleys.

Stock routing has ac compressor as first driven pulley. Crank pulls belt, first thing belt pulls is compressor. Then water pump, then alternator. Then tensioner and idler, then slack back to crank pulley.

It looks like new ac pulley location might be after the tensioner? If so, that ain't gonna work, and total fail on whoever engineered that. But maybe they did it right and I just can't see where belt routes so tensioner is at the end.

oliversok

Thank you for this info. I actually found out what the issue was. It was a wiring issue. The tap connectors were not properly ensured of wire contact. Since the a/c was relocated to the opposite side of the engine, they has to mess with the wiring and did kind of a sloppy job.

oliversok

Thank you so much for this info this is what I couldn't think of. Actually this setup has given me a lot of pain and heartache. I was having issues ever since I got the car back about a month ago.

Cliff notes of build:
- S2000 A/C compressor, all other pulleys K24
- Custom A/C bracket not perfectly aligned with all other pulleys
- Consistent screeching from A/C pulley, more so with Clutch engaged
- A/C compressor pulley has one less "teeth" than all others
- 5 rib belt (thinner) was used to accommodate pulley differences
- Custom fixed bracket tensioner used. There is no auto tensioner.
- If thicker belt is used there is chance belt will jump off of the pulleys (it has happened leaving me stranded)
- a/c will not stay engaged.

Work in attempt to fix:
- Replaced compressor clutch (didn't work)
- Replaced A/C compressor (didn't matter)
- Attempted to tensioner the belt more (one alternator smoked up because of this)
- Replaced idler pulley bearings
- "notched" the custom a/c bracket to align the a/c pulley with others better (screeching improved drastically, but still screeching when a/c is engaged)
- Got rid of the smooth surfaced idler pulley (not by choice, it got stripped)
This is what solved 90% of the screeching, but still a little with the a/c engaged
- Replaced the ac compressor pulley with a one that has the same amount of teeth as the other pulleys (still some screeching)
- Don't want to put on a thicker belt due to the possibility of it jumping

I probably did a lot more work than I should have, I kind of regret just not taking it back to the shop earlier. At this point I am thinking of just having them redo the work. I knew it had something to do with the arrangement, but didn't think of the push pull aspect of it. That makes a lot sense.

Do you guys think this is acceptable work?

oliversok

This is how it is currently

noodels

Who supplied the engine ?

Slowcrash_101

The harness connector to the ac clutch is often damaged, usually due to someone not disconnecting the connector when unbolting the compressor. It's such a common occurrence that eBay sells a replacement wiring connector to replace the broken one.

Looking at the belt routing, the AC pulley and alternator seem to be taking all the load. The OEM routing distributes tension on both sides of the belt. I'd say you're missing an idler pulley.

Car Analogy

A manual tensioner will never work adequately. Belt length changes with heat. Belt stretches with load. Watch a video of a tensioner, any engine, as engine is merely revved. Its rapidly moving all over the place.

A manual tension will always be either too loose and slip, or too tight and damage bearings. It can and likely is too loose one second, too tight the next.

Belt traction comes from 2 things. Belt surface contact area, and enough tension to keep belt closely mated to pulley.

Wider belts have more surface area. More degrees of belt wrap have more surface contact.

You are running both a narrower belt (5 rib vs stock 6 rib), and less wrap. The routing used has significantly less belt wrap than stock. Between narrower belt and less wrap you've easily got half as much belt to pulley surface contact area as stock. Half as much belt traction.

That would be if you had stock, auto tension, which you don't.

It's simply not possible to have belt not constantly causing you issues with how its been setup. You're probably overtensioning the hell out of it trying to get it to stop slipping. That causes its own set of issues, which long term can be worse than slipping belt.

So far in analysis any slipping is limited to ac compressor. So issues limited to dramatically shorter belt life and ac that doesn't work. But there is also much less belt wrap at crank. So narrower belt with less wrap risks belt slip at crank, which would result in insufficient belt speed at alternator and water pump. Your engine could overheat with the setup being used. Even if it doesn't, belt is going to fail prematurely, which at best will leave you stranded. At worst destroy engine.

It seems whoever designed the belt layout being used does not understand the basics of how ribbed serpentine belts operate.

Car Analogy

But I think there is hope. I believe it would be possible to retrofit an auto tensioner from another vehicle, in correct location of after all driven pulleys, and at same time restore much of the lost wrap using a revised belt routing. Fix all the problems.

Basically, you'd replace the idler pulley that currently sits above and between crank and compressor with an auto tensioner.

You'd add another idler pulley higher up. Basically, move the idler tensioner removed for auto tensioner up higher.

Then route belt differently. I'll make a diagram, but basically, belt would now go under crank, then up to tensioner, then down to ac, then up to new higher idler. Then continue as it does now to alternator and the rest.

You'd get drastically higher belt wrap around crank and ac, and tensioner would be in correct location. I think that would fix all yoir belt issues (assuming ac pulley now aligns with the others).

To make this work will involve finding tensioner that will physically fit, and tensions in correct direction. Tensioner pulley isn't too much a concern, as can always remove what it comes with and replace with an idler pulley of needed dimensions.

You'll also need to mock up a simple mounting bracket for tensioner.

...Looking at this further, if you can remove that black idler pulley, the one above and between ac and crank, and get me some good photos of what it mounts to, what is behind it. Anything that could interfere with a bracket that woukd get mounted there. How much space behind pulley, etc.

Also before you remove it, measure how much space between that pulley and crank pulley.

Then I can find tensioner that will work, and give details how to build tensioner mounting bracket.

Where are you located?