Thread: D4 A/C Compressor issue

Originally Posted by josh.huber

While your point is valid, no one in today's age is going to open a brand new compressor, void the warranty to swap a port plate, the seal kit and time makes it a bad idea, it works only if no others are available. This is common place on sanden SD7H15 compressors.

Speciality comes in diagnosis not modifying parts. In this case, he has sought the advice of others, the compressor is dead, he bought a condenser and drier.

The best AC guy I know operates out of a van

Diagnosis is the start of the process. He has been told that the compressor is not pumping, but no one has said definitely why.
Sanden SD7H15 compressors do not have a control valve, they are operated by a thermostatically controlled clutch.
He doesn't know that the compressor is dead, he just knows that it doesn't work.
He stated that it was not the sanden but a Denso compressor on his vehicle. The scenario I brought up is something that I used to do on a regular basis. My shop was an authorised Denso repair centre, we had the training and the experience and our clients came to us because we were able to offer a repair that was not able to be offered by many shops or mobile operators. These people came to us when they weren't able to source the parts. This was before the internet made the market a worldwide source.
I started off working from a van, and over a period of well over 20 years, grew my experience and knowledge to where I was able to do that.
What I am saying is that just because there in not a compressor with the correct part number on it doesn't mean that it can't be built from parts, at a reasonable cost.
He stated that the same compressor was on other Euro cars, but with differing ports, at a reasonable cost.
I have recommended an a/c specialist in Brisbane that has the ability and expertise to do just that.

I actually posted earlier that Id noticed the mercedes compressor was half the price and just had different pipe/port angles, so sure in an ideal world it would be nice to do as you suggest (assuming the tech gave full warranty), but im 400km from the nearest capital city, and just the mention of range rover to a mechanic around here scares them off (and who are all booked out for weeks).

Also I posted earlier, that the denso has green all under it from the front, so i know its leaking, i also know its pumping as when turned on you get hot air rather than ambient temp air, (i know its not a air mixer problem, as have gap tool) so it would seem its moving engine heated gas/fluid around the pipes, which the natrad guy did test is still there, but not making any pressure difference between H and L

[QUOTE=haydent;3171796]I actually posted earlier that Id noticed the mercedes compressor was half the price and just had different pipe/port angles, so sure in an ideal world it would be nice to do as you suggest (assuming the tech gave full warranty), but im 400km from the nearest capital city, and just the mention of range rover to a mechanic around here scares them off (and who are all booked out for weeks).

Also I posted earlier, that the denso has green all under it from the front, so i know its leaking, i also know its pumping as when turned on you get hot air rather than ambient temp air, (i know its not a air mixer problem, as have gap tool) so it would seem its moving engine heated gas/fluid around the pipes, which the natrad guy did test is still there, but not making any pressure difference between H and L[/QUOTE

Your car, your money, do as you want. If your time is worth more to you well then that's fine, and I have no problem with that. I offered a suggestion when advice was sought that's all.
I'll keep my thoughts to myself.

I'll keep my thoughts to myself.

dont, because I appreciate everyone's input


Plot twist, taking the fan and belt off today to see if possible to fit a shorter belt to bypass the pump and I worked out the sacrificial 'clutch' is actually broken ! Not knowing what it was earlier, id looked down the front of the engine and seen the front connector mechanism at an angle, and put my hand down there and it just came off.

At the time I thought it was just a vibration damper due to all the rubber bits, but being broken it means the pulley just free wheels. This is meant to break if the pump seizes to save the belt, and it would have been a 5 minute diagnosis to look at the front of the pump when engine running and see the center bolt not turning....

So I took the pulley off and it turns out the pump isnt seized, so either it momentarily seized or it broke from fatigue due to being alloy and all the pump force having to be transferred through it....

This means my pump might actually be fine (apart from the leak) and still pump ok if i replace the front plate for like $25 ! And I wont have to pull the car apart, though my order from the UK just shipped.

Also something interesting, one could actually remove this hub part on a working pump so it would free wheel between home and the gas technician, and then replace once gassed.

Here is a video that shows difference between broken and not, similar design but not same pump

BROKEN ac compressor “sheer hub” drive plate clutchless denso (variable displacement) - YouTube

Here is a photo of the same looking part I pulled off my car, with the broken shear points marked.

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what it looks like from front

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And the tool you would want to get the hub plate on/off without risk of breaking the clutch, though teh LR manual doesnt mention one, I would use one.

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Though maybe they allude to it but not show it

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So Ill try getting another hub plate domestically from a wrecker or denso supplier, otherwise china, as id be happy to put the new parts in the shed for now if I can get away with it for now at least...

** Update, the pump does seize intermittently I can spin it like 4-10 times, very smooth, no problem, and then it randomly just locks up in that direction. I also tried getting the broken hub nut off (yes I know its reverse thread like the fan), but it was seized so bad i rounded and bent the baby 7mm head it has on the end of the shaft, so that would make the pump irreparable anyway. Im guessing when the pump seized and broke the hub it torqued the nut up crazy tight...

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So those that had looked at it for you weren't on the ball. Other than the one who said compressor is cactus but for the wrong reason. It wasn't pumping hot gas around at all. It wasn't pumping period.

Originally Posted by LuckyLes

So those that had looked at it for you weren't on the ball. Other than the one who said compressor is cactus but for the wrong reason. It wasn't pumping hot gas around at all. It wasn't pumping period.

Only person I had look at it was the natrad guy who didnt look at where the pump was, super busy, just tested the gas pressure with the AC off and on, enough to say there was enough gas in it, and that the pump wasnt kicking in as no higher pressure on the high side. I could see this too with the gap tool, as it gives a pressure readout from the H side. He thought it could have been electrical too, but I could see it didnt seem that way from gap readings and lack of errors, so he agreed it could be the pump but was hesitant to say it to me right away.


It was just my theory that it was pumping engine heated liquid around as an explanation for the hot air, but now that cant be, as pump not rotating. But what I think might have been happening instead is just thermosiphon (due to the evap being higher than the pump), being turned on and off by the control valve in the pump which is likely still working, I dont think theres any other electric control of the ac system as with AC off, fan vent air still goes through the cabin ac radiator evaporator.


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also just to keep this a little relevant to the topic title, (i will move back to the l320 forum in a bit) it seems the d4's / 2.7 have a very similar looking denso and that is an engine option in my l320 manual and the hub instructions look identical, though the principles ive been going over would apply to the sanden one too LR013841 - Air Con Compressor for Discovery 4 2.7 TDV6 | LR Parts