How do you get to the AC compressor to replace it?

9364 Views 15 Replies 6 Participants Last post by vadsoom, Sep 16, 2021

recyn

Discussion Starter · Sep 2, 2020

Hi,

I am trying to replace my AC-compressor on a Smart fortwo 451, 2008.

I have tried to reach the screws holding the ac-compressor from underneath the car and from the passenger rear side (took the splash protecting black fender out) but cannot get to them.

Any suggestions?

Thank you

1 - 16 of 16 Posts

gtdump

· #2 · Sep 2, 2020

If you're doing this kind of work I highly recommend a set of lowering bolts (450 589 00 62 00) sometimes referred to as "Record Release" bolts.
Bolt lengths not including washer are 26 cm and 30 cm; thread size is M12x1.5. Grade 8.8. threaded length 50mm
The official ones aren't especially cheap and a set could be fabricated, but once you figure in the time to make them the savings seems to shrink.
With these, you can lower the subframe assembly and be able to reach the pump without a lot of trouble, I can't imagine doing it without lowering.
I think mine were about $70 including shipping.

This post touches on it, but there are probably better examples in other threads. I still have the whole thing apart if additional images would be helpful.

www.smartcarofamerica.com

2010 Smart Fortwo Engine Sub-Assembly Removal.

A while back I picked up a junker for parts. It's a 2010 and for the most part it's in good shape but was sold as having a bad engine, so there's no telling exactly what all is wrong with it. I'm a busy person and it can take me a while to get around to finishing some tasks, this one included...

www.smartcarofamerica.com

www.smartcarofamerica.com

Jo e Lefors

· #3 · Sep 2, 2020

recyn said:
Hi,

I am trying to replace my AC-compressor on a Smart fortwo 451, 2008.

I have tried to reach the screws holding the ac-compressor from underneath the car and from the passenger rear side (took the splash protecting black fender out) but cannot get to them.

Any suggestions?

Thank you

Here is one way.

gtdump said:
A pair of curved needle nose pliers were handy for getting some of the hose clamps, others didn't need it; three hoses in total.
Once that was disconnected, I could remove the subassembly and wheeled it over to my workshop area...
View attachment 63906

Now I need to start separating the motor from the assembly and the transmisison...
View attachment 63907

Gtdump knows how
Good luck

gtdump

· #4 · Sep 3, 2020

I will note that the bolts will allow it to be lowered farther than some of the connections to the rest of the car allows, so be mindful of the lines and harnesses as you separate the two. Should be able to get to it easily without disconnecting much, if anything.

recyn

Discussion Starter · #5 · Sep 3, 2020

Hi gtdump,

Thanks for your advice. I have never heard of these bolts, cannot imagine how they are used.

I will look into getting these bolts and how to use them. It looks wilde and difficult on the photo you attached to take out the whole subframe.

Regards,

Jo e Lefors

· #6 · Sep 4, 2020

recyn said:
Hi gtdump,

Thanks for your advice. I have never heard of these bolts, cannot imagine how they are used.

I will look into getting these bolts and how to use them. It looks wilde and difficult on the photo you attached to take out the whole subframe.

Regards,

I don't think you have to drop the whole subframe, but it seems like you "may" have to drop the engine somewhat. Keep us updated on your progress.
Good luck & have a safe Labor Day

gtdump

· #7 · Sep 4, 2020

3

recyn said:
Hi gtdump,

Thanks for your advice. I have never heard of these bolts, cannot imagine how they are used.

I will look into getting these bolts and how to use them. It looks wilde and difficult on the photo you attached to take out the whole subframe.

Regards,

Here's a picture of the bolts, they're just long hardened bolts to allow separating the subframe which contains the engine and transmission from the main body. 12" steel rule for scale.

Here's a shotof a subframe, minus the engine and trans, with blue arrows pointing to where the bolts would go at the corners. There are shorter bolts in there which normally secure the subrame to the main body, but by removing those and replacing them with the lowering bolts/Record Release bolts you can then raise the main body up off the subframe by about 8 inches, which will give you room to work.

Here's a shot of them in use. If you look toward the back of the car you can see one of them sticking through the subframe.

See less See more

jwight

· #8 · Sep 4, 2020

Here's the official smart illustration of the rear module in lowered position...

See less See more

Reactions: 1

recyn

Discussion Starter · #9 · Sep 4, 2020

Wow, Thank you so much Gtdump, Jo e Lefors and jwight for your detailed instructions.

As far as I understand it now, you unscrew the 4 screws that are holding the subframe and replace them with the record release bolts (they seem to have two different lengths?). Then you can lift up the body of the smart car and get access to the ac compressor.

It is very good to know that you can get access to engine parts you otherwise could not get to.

However, I would be afraid that the body could collapse on me while doing work in the opened up gap since I do not have a lift to raise the body. I would be reluctant to trust a pneumatic car jack.

Is there no easier solution, like taking off the oil pan or removing the alternator to get to the ac compressor?

Regards, and multiple thanks for your detailed advice so far.

Jo e Lefors

· #10 · Sep 4, 2020

Afraid that's the way it's done.
It the cost of owning a micro car that can be parked in small spaces.
Everything is packed into a small space.
I would change both belts and anything else while you have the engine lowered / body raised.
Again good luck.

gtdump

· #11 · Sep 4, 2020

recyn said:
Wow, Thank you so much Gtdump, Jo e Lefors and jwight for your detailed instructions.

As far as I understand it now, you unscrew the 4 screws that are holding the subframe and replace them with the record release bolts (they seem to have two different lengths?). Then you can lift up the body of the smart car and get access to the ac compressor.

Yep, two different lengths. I gave the measurements in an earlier post.

recyn said:
However, I would be afraid that the body could collapse on me while doing work in the opened up gap since I do not have a lift to raise the body. I would be reluctant to trust a pneumatic car jack.

It's a risk noted in the service manual. Anytime you put a car on a lift, jacks, stands, or the like there's a chance of failure; not trying to hide that. What I have done is when I separate the subassembly I put pieces of 4x4 in the gap between the two so that should my cribbing fail and the car somehow slip it won't crush me; you can see the blocks in some of the images in my subassembly thread. It doesn't remove all risk, but it does mitigate a lot of it. Anytime something feels sketchy think of your safety first and examine it for ways of making it safer or don't do it. I don't work on cars on jacks, I don't get under a car on just jackstands, and I don't put my hands in places where I think there's a risk of me losing them. One can do all this work safely, you just have to understand what you're doing and how to protect yourself.

recyn said:
Is there no easier solution, like taking off the oil pan or removing the alternator to get to the ac compressor?

Regards, and multiple thanks for your detailed advice so far.

There are probably other ways. Having worked on the car before and after having the bolts, there are some tasks which the bolts make much, much easier. You could try disconnecting the motor mount that attaches to the trans and lowering it that way; it might gain you the space you need I don't know.

When I was disconnecting the coolant hoses I had to get under the car. I had cribbing under the car at 3 points along with stands. It would take a cascade of failures to crush me, but it could happen.

See less See more

recyn

Discussion Starter · #12 · Sep 5, 2020

Thank you so much for your help guys.

I am glad to have learned now about how to lower the subframe for serious repairs using the lowering bolts.

I also appreciate that you were looking for other ways to get to the ac compressor.

I like to have everything working properly in my smart but seeing that it is not that hot outside anymore, I might just open the window instead of having a luxury air conditioning in my car. When it gets hot again next year or if I have an urgent "non luxury" repair that requires lowering the subframe I have gotten excellent instructions from you guys to work myself through it. And I might replace the ac compressor then as well. But this is serious repairing smarts.

I felt empowered by successfully replacing my starter motor (what just took 10 minutes, (am I slow?)), but this subframe lowering is another level of repair work.

Best Regards,

gtdump

· #13 · Sep 5, 2020

recyn said:
Thank you so much for your help guys.

I am glad to have learned now about how to lower the subframe for serious repairs using the lowering bolts.

I also appreciate that you were looking for other ways to get to the ac compressor.

I like to have everything working properly in my smart but seeing that it is not that hot outside anymore, I might just open the window instead of having a luxury air conditioning in my car. When it gets hot again next year or if I have an urgent "non luxury" repair that requires lowering the subframe I have gotten excellent instructions from you guys to work myself through it. And I might replace the ac compressor then as well. But this is serious repairing smarts.

I felt empowered by successfully replacing my starter motor (what just took 10 minutes, (am I slow?)), but this subframe lowering is another level of repair work.

Best Regards,

My AC doesn't work either, I'll get to it eventually.
That aside, are you certain the compressor is the issue? I believe the failure on mine may be the controller in the cabin as I've cleared a couple of codes about it, but I haven't spent a lot of effort diagnosing it yet. Would hate to see someone go through all the work of replacing the compressor and have it not be the actual problem.

recyn

Discussion Starter · #14 · Sep 5, 2020

It is a while that I am getting back and forth trying to fix my AC. I started trying to fix my AC by replacing the compressor clutch since it do not engage anymore even after I had refilled the cooling system with refrigerant several times.

After this repair the AC worked for a while but then I heard some strange grinding sound coming from the compressor. Therefore I think it is time to take a closer look at it and maybe replace it.

I might take off the compressor belt again to see whether the bearings are gone. But this is unpleasant work to do and I am trying to avoid it

Does the AC system have its own control unit?

Regards,

dreyabram

· #15 · Sep 15, 2021 (Edited)

I can give you one simple piece of advice. No need to change any air conditioners. You just need to keep an eye on them. So I changed my air conditioner once, and then I really regretted it. He began to work poorly. At first I thought it was broken, but then I realized how much I was wrong. Literally six months later, I had the same problems with the new air conditioner. I was under terrible stress at the time. It's good that I was completely desperate and turned to one service that helped me cope with the problem. . Thank them for their help! The best service for aircon chemical overhaul!

vadsoom

· #16 · Sep 16, 2021 (Edited)

recyn said:
Does the AC system have its own control unit?

It depends on how you define “control unit.” The AC system is very simple. There is a pressure switch inside the R134a path to determine if there is enough coolant to allow the system to start. If yes, the AC button on the dash triggers a a relay that engages the AC compressor clutch. There are no other controls or circuits involved. Temperature regulation os done by blending warm air with the AC air using the system’s blend doors.

Does this help?

Edit: crap… why are all of these old posts popping up as undead on Tapatalk? It made me think this was a fresh question.

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