AC fuse frustration

[gr8eyes]

Hi Everyone,

This is my first Post though I've been reading and learning from this site for quite sometime.

I've spent 6 hours poring through all the Issues with the AC system and have not been able to find an answer to my problem, so I'm hoping some of the brilliant minds on this site can come up with a brilliant answer.

I have a 93 model that is all original with 84,000 miles on it.

Saturday on my way home from a 30 min drive it started getting stuffy in the cabin. finally realized the Ac was blowing warm air through driver AND passenger vents, regardless of speed.
When I got home found both condensers were working and so was the blower. Checked the fuses under the hood and they were good
Checked the fuse in the engine bay labeled HAC clutch was blown, and thought that was easy
I replaced it and went for a quick drive but it was a no go.

Got back home and the fuse was blown again, so my question is what could be making this fuse blow.

BTW I did check the site glass of the refrigerant lines and it appears to be clear.

Thanks in advance for any possible leads.

gr8eyes

 

[JohnWayne]

Do you know how your CCU board is functioning? Has it been repaired before?

 

[BTL3.0]

Another thing to check is the ac clutch field coil. If there are black goo splatter, chances are the field coil need replaced. I had this issue with my 98 honda civic. Fuse keep popping when ac are turn on. May be unrelated to nsx but doesnt hurt to check.

 

[gr8eyes]

Do you know how your CCU board is functioning? Has it been repaired before?

John Wayne thanks for the reply

No I don't know if its functioning and its never been serviced before

I'm not a mechanic at all so if this gets too involved ill have to take it to the dealer

gr8eyes

 

[gr8eyes]

Hi BTL

I'll see if I can figure out where the clutch field coil is and check it

Unfortunately I have very limited mechanical ability. Now if you need your eyes checked I can do that. LOL

 

[Old Guy]

BTL3.0 is probably correct. The easiest way to check is to disconnect the clutch coil at the compressor, install a new fuse and then start up the air conditioner. You won't get any cool air; but, if the fuse does not blow that pretty much means the clutch coil is shorted out. If the fuse does blow, then it may be the compressor clutch relay in under hood relay box B (much cheaper than a new clutch).

The connector for the clutch coil on the compressor is C143. It is a grey single wire plug and the wire going into the plug should be red (according to my 1997 wiring diagram). It is mounted on the same bracket that holds the oil dipstick. Should be easy to find.

 

[JohnWayne]

John Wayne thanks for the reply

No I don't know if its functioning and its never been serviced before

I'm not a mechanic at all so if this gets too involved ill have to take it to the dealer

gr8eyes

Check what Old guy and BTL said first.

The CCU removal is easy and you dont need to take to the dealer. Brian K here on prime repairs the boards.

 

[gr8eyes]

BTL3.0 is probably correct. The easiest way to check is to disconnect the clutch coil at the compressor, install a new fuse and then start up the air conditioner. You won't get any cool air; but, if the fuse does not blow that pretty much means the clutch coil is shorted out. If the fuse does blow, then it may be the compressor clutch relay in under hood relay box B (much cheaper than a new clutch).

The connector for the clutch coil on the compressor is C143. It is a grey single wire plug and the wire going into the plug should be red (according to my 1997 wiring diagram). It is mounted on the same bracket that holds the oil dipstick. Should be easy to find.

Thanks everyone I'll give those a try one night this week and see what comes uo

 

[gr8eyes]

Hi guys, I finally had some time to run through the suggestions.

1 The compressor doesn't have a lot of black "goo"around it maybe 1-2 small spots of something around it.

2 I disconnected the connector and stated the car and turned on the AC. The fuse did not blow. I hooked the connector back up and started the car w/o the AC on and the fuse was still good.
I then turned the AC on and the fuse blew.

CONCLUSIONS:?????

1. Can we assume the relay mentioned above is not the culprit, or is that still a possibility?
2. Does this definitively point to the Compressor/clutch unit as the culprit?

Thanks for any insight?

Glenn

 

[Old Guy]

Preliminary diagnosis suggests a clutch problem, not the relay. If you have a multimeter tester and if the service manual specifies a resistance for the clutch coil, you could connect the multimeter to the clutch connector plug and measure the coil resistance. If the value is a lot lower than the service manual value, then you have a definitive diagnosis of a clutch coil problem.

It is possible that the clutch coil problem is caused by chaffing on the wire from the connector to the clutch rather than on failure of the actual coil. I don't know whether you can effectively do that inspection of the wire with everything still mounted in the car.

 

[gr8eyes]

Preliminary diagnosis suggests a clutch problem, not the relay. If you have a multimeter tester and if the service manual specifies a resistance for the clutch coil, you could connect the multimeter to the clutch connector plug and measure the coil resistance. If the value is a lot lower than the service manual value, then you have a definitive diagnosis of a clutch coil problem.

It is possible that the clutch coil problem is caused by chaffing on the wire from the connector to the clutch rather than on failure of the actual coil. I don't know whether you can effectively do that inspection of the wire with everything still mounted in the car.

Sounds like I may as well bite the bullet and replace the condenser.

Now ill need to decide if I can do it or send to the dealer. After looking at the manual procedure for replacement the only difficult part appears to be getting to it and capturing the refrigerant, (R-12). And then deciding if I should go ahead and switch to R134.

It does appear that front crossmember would be a bugger to get out of the way

Any suggestions??? I see a new denso compressor can be had for around 250.00 dollars

Glenn

 

[BTL3.0]

View attachment 145848
Here is the clutch/field coil from my civic, which was doing exactly what you described.
Unplug coil wire, replace fuse, start car, turn ac on... fuse ok
While car running, ac still on, plug coil wire back in.... fuse blown
You can see the coils are exposed. The protective coating got so hot it splatter on the ac belt. Also notice the clutch is bad, which needs replacing.

Here is a new oem coil.
View attachment 145849

 

[gr8eyes]

View attachment 145848
Here is the clutch/field coil from my civic, which was doing exactly what you described.
Unplug coil wire, replace fuse, start car, turn ac on... fuse ok
While car running, ac still on, plug coil wire back in.... fuse blown
You can see the coils are exposed. The protective coating got so hot it splatter on the ac belt. Also notice the clutch is bad, which needs replacing.

Here is a new oem coil.
View attachment 145849

Thanks guys for your replies. I've posted 2 times but haven't made it on yet, so i'll post again.

The actual replacement of the compressor seems like the way to go but there are a couple of Obstacles.
1) Getting to the compressor requires moving some crossmember below the compressor. Not sure i'm capable of that then
2) recovering the refrigerant evidently requires special equipment unless there is a way to cap those hoses coming into the compressor to prevent leakage and then top the system back off with R12. But I think most people here would advise draining and replacing the system with R134

I think I could save about 1,000 dollars if I do it myself so I'm in a real quandry.
Advice would be appreciated



Glenn

 

[gr8eyes]

Sory about the delay

I've posted 3 times and they havent shown up. I'll try once more

Thanks Old Guy and BTL3.0 for your responses

Obviously I'll have to replace the Compressor and it looks simple enough but for 2 things

1) It looks very hard to get to. I think the manual says you have to get to it from beneath and you have to move some kind of crossmember
2) I dont have a collection system for the refrigerant. If i could figure out how to plug the hoses to the compressor till I got them reattached to the new one, it would be great of course I'd still be using R-12. Changing to R134 sounds complicated

So the question is should I tackle this myself and save the 1,000 dollars or bite the bullet and take it to the dealer, advice , encouragement, discouragement are all welcome

Glenn

 

[Kaz-kzukNA1]

As long as your compressor is not making loud noise (you won't know this until you can engage the A/C CL) or seized, there is no need replacing the compressor or even disturb the A/C line.
Do you know whether your compressor was ever removed (but without disconnecting the A/C pipe) or not for a certain service?

If not done properly, the field coil wire held by the metal clip on the compressor body could be damaged creating short circuit.
If this was the case, you don't even need to replace the field coil but you won't have enough space for inspection so best to remove the compressor but without disconnecting the A/C lines.

Presuming that your compressor CL is still healthy, you can just replace the field coil.
It's available from your local Acura/Honda.
Strictly speaking, the field coil winding is different between R12 and R134a (R134a requires higher CL force) but same geometry so either type can be used.
In fact, Acura/Honda already superseded the original parts no. and only later spec available at about US$100.

For the similar price, you can get the field coil/pulley/CL set from RockAuto but please make sure to select the correct pulley design.
I think RockAuto is showing the wrong pulley info for 97+ model but as yours is R12 and thus 91 model, so doesn't matter as the one shown on their web site is good for the 91 - 96.

As you suspected, you need to remove the long grey coloured front cross beam under the eng bay.
Obviously, you need to remove several things before that such as the shift cable/AT selector cable, etc.

Imagine that you are standing under the car and looking up at the engine/ceiling with your back facing the front of the car.

A/C compressor is held by just 4 off 12mm bolts (marked blue arrow) with 22Nm torque and one of them close to the fire wall towards the exh manifold has very limited space so may struggle but not difficult.

No need to disconnect the A/C line from the compressor.

However, the compressor is fairly heavy and since you are keeping the thick A/C line connected (sprung effect), make sure to hold it before removing the last bolt as it will swing towards your head.

Once the compressor is off the bracket, make sure to hung it somehow to minimise the stress on the A/C line.

The CL/pulley/field coil assy is held by small bolt at the centre of the pulley.
Thread lock applied at the factory so be creative when loosening the centre bolt but do not pull it out from its place yet.

In order to create specified gap between the pulley and the CL, one or multiple washer(s) is/are used as the shim(s) and it/they will fall out when you remove the centre bolt so be prepared and don't lose it/them.
Though, not a big issue as you can adjust it later but you may not have the ideal thickness washer in stock.

Just read the workshop manual and understand the process before deciding whether to go for the DIY or ask someone to do it for you.

Good luck.


Kaz

 

[gr8eyes]

As long as your compressor is not making loud noise (you won't know this until you can engage the A/C CL) or seized, there is no need replacing the compressor or even disturb the A/C line.Do you know whether your compressor was ever removed (but without disconnecting the A/C pipe) or not for a certain service?If not done properly, the field coil wire held by the metal clip on the compressor body could be damaged creating short circuit. If this was the case, you don't even need to replace the field coil but you won't have enough space for inspection so best to remove the compressor but without disconnecting the A/C lines.

Presuming that your compressor CL is still healthy, you can just replace the field coil. It's available from your local Acura/Honda.Strictly speaking, the field coil winding is different between R12 and R134a (R134a requires higher CL force) but same geometry so either type can be used. In fact, Acura/Honda already superseded the original parts no. and only later spec available at about US$100. For the similar price, you can get the field coil/pulley/CL set from RockAuto but please make sure to select the correct pulley design. I think RockAuto is showing the wrong pulley info for 97+ model but as yours is R12 and thus 91 model, so doesn't matter as the one shown on their web site is good for the 91 - 96.

As you suspected, you need to remove the long grey coloured front cross beam under the eng bay.Obviously, you need to remove several things before that such as the shift cable/AT selector cable, etc.

Imagine that you are standing under the car and looking up at the engine/ceiling with your back facing the front of the car.A/C compressor is held by just 4 off 12mm bolts (marked blue arrow) with 22Nm torque and one of them close to the fire wall towards the exh manifold has very limited space so may struggle but not difficult.No need to disconnect the A/C line from the compressor.However, the compressor is fairly heavy and since you are keeping the thick A/C line connected (sprung effect), make sure to hold it before removing the last bolt as it will swing towards your head. Once the compressor is off the bracket, make sure to hung it somehow to minimise the stress on the A/C line. The CL/pulley/field coil assy is held by small bolt at the centre of the pulley.Thread lock applied at the factory so be creative when loosening the centre bolt but do not pull it out from its place yet.In order to create specified gap between the pulley and the CL, one or multiple washer(s) is/are used as the shim(s) and it/they will fall out when you remove the centre bolt so be prepared and don't lose it/them.Though, not a big issue as you can adjust it later but you may not have the ideal thickness washer in stock. Just read the workshop manual and understand the process before deciding whether to go for the DIY or ask someone to do it for you.Good luck.Kaz

KazThanks for the great infoThe Compressor is not making any noise, and its never been serviced as far as I know. Its a 93 model I bought in 95. It had 24,000 on it when I bought it and now has 84,000. Its a completely stock car.So you don't think I should just replace the whole compressor , just the pulley? And check the wires. BTW the pulley spins fine and no noise.Glenn

 

[Kaz-kzukNA1]

Hi, Glenn.
From what you wrote, not sure we are referring to the same thing so I'm going to use several photos.

The pulley is mounted on the compressor body at the protrude section via the bearing and the pulley itself doesn't have any direct connection to the compressor shaft.
While the engine is running, it's continuously spinning by the A/C belt regardless of the A/C CL relay status (A/C On or Off).

The CL (the pressure plate with friction disc that the field coil pulls against the pulley when energised) is the only part that is directly connected to the compressor shaft through the spline and the centre bolt.
It won't start spinning unless the CL is engaged.

In order to transfer the rotational force of the pulley to the compressor shaft, the field coil must be energised and press the CL/pressure plate against the friction material on the side of the pulley.
This is the reason why there is specific gap between the pulley friction material and the CL.

Once the CL is pressed against the pulley, this will start rotating the compressor shaft resulting in compressing the refrigerant and the A/C starts working.


So, unless you removed the A/C belt, you won't be able to spin the pulley.

You can rotate the CL (which results in spinning the compressor) with your hand when the field coil is not activated while the engine is stopped but you would feel some friction and won't spin freely.
You won't be able to tell whether the compressor is making noise or not at such low speed.
You must activate the CL and spin the compressor at the pulley speed.

The definition of the year model is different depending on the market area but if it's 93, by that time, all NSX A/C left the factory with R134a system so not sure why you mentioned the R12.
Can be easily checked by looking at the Hi/low pressure port, etc.

If replacing the compressor, you will be forced to replace other parts and personally, I would flash the entire system before doing so.
You need to check for any leakage otherwise you could damage the new compressor.
One of the most common reason for compressor failure/noise is running the system with very low refrigerant.
Without proper equipment, it's no longer a quick DIY and depending on your local regulation, you must be qualified to carry out some of the tasks.

It's not so common for the field coil to fail on our NSX but you have short circuit somewhere so there could be a good reason to consider replacing the compressor but otherwise, just replace the field coil (not the pulley) and don't disturb the A/C lines or the compressor.


Kaz

 

[gr8eyes]

Kaz

Thanks for the reply. I was just assuming it was R-12 because it was an early car. I'm glad that was a wrong assumption.

After looking at the great photos and explanation I think i'll try just replacing the field coil then have a shop charge the system with new R 134

I ill check around for a new aftermarket coil

I'm going to have to find the time and get psyched to get started

I appreciate everyone help and suggestions, this kind of thing is not most eye doctors realm of expertise LOL


Glenn

 

[gr8eyes]

Update

Well I'm whipped on my compressor clutch/coil replacement after spending an hour trying to get the crossmember beam off. I took all the bolts off I can see but it won't budge

This is really disappointing I thought this was going to be very straightforward especially based on the great pics and instructions by KAZ and Old Guy.

And to top it all off I got up off my back and got Vertigo and am feeling like I'm going to throw up. Heat has a lot to do with that I think

BTW BTL3.0 and Old Guy were right, While under the car I saw that black tar like sponge thrown off by the pulley. Good diagnosis guys

Well acura will be 1.000 dollars richer, Hopefully they will use the coil
/pulley assy I bought from Rock Auto.

Glenn

 

[jwmelvin]

[MENTION=33899]gr8eyes[/MENTION] did you take the bolt out of the front motor mount? That bolt holds the mount to the cross beam. Other than that, some have posted that using a ratchet strap to squeeze the two frame rails together can help because the car essentially bows down in the middle when lifted, putting the beam in tension.

 

[gr8eyes]

@gr8eyes did you take the bolt out of the front motor mount? That bolt holds the mount to the cross beam. Other than that, some have posted that using a ratchet strap to squeeze the two frame rails together can help because the car essentially bows down in the middle when lifted, putting the beam in tension.

No I don't guess I did, is that right in the middle of the beam? I just noticed from KAZ picture that there appears to be 2 fin like projections with a bolt going through it but I can't get anything up in there to remove the bolt.

Glenn

 

[jwmelvin]

Yes that's the bolt. Can you get at it from the top?

 

[gr8eyes]

I don't know, I'll look when I get home. If I recall I don't think there is enough room between the engine and the bulkhead to do anything down there but i'll check this evening.

 

[gr8eyes]

Do you know if I have to have the engine on a hoist before I undo that front engine mount bolt?

 

[jwmelvin]

Do you know if I have to have the engine on a hoist before I undo that front engine mount bolt?

I wouldn't worry about it. There are three other engine mounts.