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Greetings from down under, Eric and all members,
I’m new to this forum but I enjoy and have been watching the ETCG You Tube videos and learned a lot from them. More power to you.
My car is a ’91 Prelude (BA4) 2.0 4WS ( Engine is a B206A). Two days ago, I had the AC professionally evacuated, vacuumed and recharged with the R134a refrigerant. It worked perfect for a day blowing really cold air and running smoothly.
The next day when I turned the AC on , it wont cool anymore and the rpm literally fluctuates up and down every second! ( similar to someone revving the gas up and down rapidly).
It only happens when I press the AC button on with the cabin fan on. My mechanic observed this while happening and he said the compressor does not even engage or turn at all during the fluctuations. Mechanic checked the refrigerant and it was still charged and no leaks detected in the system.
When the AC is off, the rpm is normal and no issues whatsoever.
Apologies in advance if this has been posted before, I searched the archive on this forum the best I can, but did not seem to find a matching topic or I might have missed it.
Any help anyone can offer in shedding some light as to why the above problem is happening is much appreciated. I have the car booked in to have this problem looked at, but I would at least want to have an idea beforehand of what is happening here – specially from people who might have experienced the same issue and solved it successfully.
Thanks
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I suppose its possible that the compressor clutch locked up, since the mechanic said the compressor wasnt turning.
Is the belt still on the pulley? (Check condition of belt)
If it is clicking and switching rapidly, It could be the AC Pressure Switch, but the compressor would still turn when engaged.
Something is causing the A/C compressor clutch not to engage. It could be several things – something for your mechanic to look at. Anyway, since the compressor puts load on the engine the rpm would drop without compensation. So, the computer ups the rpm when the compressor is commanded to run but the compressor doesn’t run. Hence the changes in rpm.
Checked the belt and although belt still looks ok visually, it could probably do with a new one. Tried adjusting the old AC belt deflection to the Honda spec of around 9-11 mm. Here is what happened after:
1. First time turning the AC and fan on after belt adjustment – the rpm remained stable but compressor still not turning at all.
2. Turned the car engine off then restarted, then AC on – the rpm rapidly fluctuates again and still compressor not turning.Might be on to something here – since the rpm fluctuation was somewhat affected by the AC belt adjustment even if its only shortlived?
Tried tightening the belt a tad more ( not too tight though) repeated steps 1 and 2 and same thing happened.Makes perfect sense.
What do you think are the basic culprits that could cause the AC compressor not to engage in this type of car? – assuming that the compressor is still ok and that there are no significant high/low pressure deviation in the AC system?
[quote=”Cwwprelude” post=126125]Makes perfect sense.
What do you think are the basic culprits that could cause the AC compressor not to engage in this type of car? – assuming that the compressor is still ok and that there are no significant high/low pressure deviation in the AC system?[/quote]
The compressor clutch locks the pulley to the compressor crank shaft when when the electromagnet behind the pulley is energized. So, bad wiring to the magnet or wiring unplugged is a possibility. The coil in the magnet could be open. Sometimes the clutch will wear to where it can no longer pull in far enough to engage.
One of the A/C lines will have a pressure switch on it. Refrigerant and the oil flowing with the refrigerant cools and lubricates the compressor. If the pressure is too low the switch shuts off the compressor to prevent damage to the compressor. A bad pressure switch or bad wiring to the switch will cause the compressor not to run. Of course low pressure will do this too.
Other than that maybe something failed in the cabin controls and no power is being sent to the compressor clutch electromagnet. It could be a bad relay or blown fuse.
The belt if still in one piece is going to run the compressor. It might slip or squeal but the compressor will try to run.
[quote=”barneyb” post=126139][quote=”Cwwprelude” post=126125]Makes perfect sense.
What do you think are the basic culprits that could cause the AC compressor not to engage in this type of car? – assuming that the compressor is still ok and that there are no significant high/low pressure deviation in the AC system?[/quote]
The compressor clutch locks the pulley to the compressor crank shaft when when the electromagnet behind the pulley is energized. So, bad wiring to the magnet or wiring unplugged is a possibility. The coil in the magnet could be open. Sometimes the clutch will wear to where it can no longer pull in far enough to engage.
One of the A/C lines will have a pressure switch on it. Refrigerant and the oil flowing with the refrigerant cools and lubricates the compressor. If the pressure is too low the switch shuts off the compressor to prevent damage to the compressor. A bad pressure switch or bad wiring to the switch will cause the compressor not to run. Of course low pressure will do this too.
Other than that maybe something failed in the cabin controls and no power is being sent to the compressor clutch electromagnet. It could be a bad relay or blown fuse.
The belt if still in one piece is going to run the compressor. It might slip or squeal but the compressor will try to run.[/quote]
I’ll have these pointers checked by the mechanic. Being an old car, I thought might help him solve the problem quicker with some research specific to this car. I’ll have the accessory belts changed as well while we are at it. Thanks for the responses, I will post an update on what the shop finds out.
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