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AC is cold until higher speeds / higher engine temp

AC/Heater 
4K views 21 replies 13 participants last post by  hondacivicnut 
#1 ·
Hi guys, sorry for another AC thread but my issue seems pretty weird.

Just had my AC re-gassed on Thursday and they assured me there were no leaks. Driving around afterwards, I could confirm that nice ice cold air was blowing out my AC.

On Friday, I had to drive to Reading, and after about 10-15 minutes, hit the motorway and the ice cold air stopped blowing, making way for tepid air which unsurprisingly, made my drive very uncomfortable.

Driving back this morning, exact same issue occured. I was driving around and ice cold air was blowing, but by the time I hit the motorway, the ice cold air had stopped and the drive became very uncomfortable.

Could this be something to do with by the time my engine has warmed up, it's starting to overheat something? The temperature gauge doesn't seem out of the ordinary and I have no warnings.

What could be the fault here? I had my relay replaced last summer when I had my aircon regassed (which seems pretty frequent to me).

Thank you
 
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#2 ·
Just to update here. Was a fairly brisk 11 'C this morning. Driving to work, 15 minutes spent on an A road doing about 30-40, nice cold air pumping out.

Hit the M5 (averaging 70) and immediately, the air looses its chill and reverts to a lukewarm air. After the motorway section (about 10 minutes), I was back at about 30-40 on an A road and it didn't revert back. I'll see what it's like on my commute home today.

and I haven't done anything like left air recirculation on, or disabled my AC.
 
#3 ·
Hello from me too. I haven't entered Civinfo for a few months and I came for exactly the same issue as the thread starter. Absolutely the same problem occurred to me a few times since the weather got hot.
I noticed that pushing the A/C button turns on the compressor, but no cold air comes out. Suddenly when we left the motorway and went back to city traffic, the cold air came back on. I haven't checked levels of freon, but when there is no problem, the air is really cold...
 
#5 ·
I will be seeing an air con expert tomorrow and will try to remember to ask him for you both.
My guess would be a fault in the re circulation system which should be turned on automatically in hot weather, if it isn't closing off the outside air the system has to cool warm air from outside which it can cope with at low speeds but at higher speeds it can't refrigerate the incoming rush of air quickly enough.
 
#9 ·
That's very kind of you. Thanks mate

99% sure it will be the compressor clutch. Check this link for the fix. I drove around for months with exactly those symptoms until I finally got fed up enough to sort it. It's a fairly simple fix, just a bit fiddly.
Thanks for the link, I'll read through that now and have a look.

@popebenedict , I'd try the relay first. PM me your address and I'll post one down to you. Got two spares from when my 8G was playing funny buggers.
I'm very grateful for the offer but I'm pretty damn sure it's not the relays fault because it does seem to work when I'm doing lazy driving around town. I think other people would benefit more from your offer.

Again, very grateful. Cheers mate.

Agree with this - my AC was intermittent and the shim for the compressor clutch was at fault.

Just have some spare shims at the ready. Also remove the washer bottle, takes about 5 mins but gives much better access.
Thanks for the info, I will investigate further.
 
#12 ·
I believe it is 38912-PE1-702. I have ordered but haven't collected it yet...
I get the part number from parts-Honda.uk. I cannot post the link directly as I haven't had enough posts yet. If you search for compressor or clutch set, you will have a picture with all parts listed.
 
#15 · (Edited)
Just been to a local air con garage and they're advocating replacing the whole compressor.

How much should I expect to pay for this? From what I could tell, it looked very non-trivial to get access to the compressor because of the undertray blocking everything.

[edit] I asked the mechanic regarding replacing the shims and he essentially said it wasn't going to happen.

[edit2] Got a quote for £400 (200+200 labour) for a compressor replacement at my other garage. Does that sound about right?

Cheers
 
#17 ·
Compared to a fiver for some shims? Not that good :)

Personally I'd have a go at the shim fix first, then start spending money. It's not a hard job, a few bolts for the undertray and one for the clutch plate. You'll need shims, a piece of wood/metal to wedge the clutch plate, and ideally a feeler gauge to measure the gap (£2ish on ebay). I can probably send you a few shims if I can find the ones I used. I bought a pack of r/c car ones off ebay and only used one or two.
 
#19 ·
I'm not convinced this is a compressor problem.

And I'm not sure how the guys that refilled the system could be sure there was no leak without performing a pressure test on the system (rather than simply witnessing that it held a vacuum during outgassing, which is often wrongly taken as a sign that the system won't leak when under pressure). Was a UV tracer included as part of the refill?

In the wiki there are instructions on using the HVAC built-in diagnostics. One of the parameters that can be displayed is system gas pressure,cwhich should confirm whether your system gas list any refrigerant.
 
#21 ·
There is no one final solution, as the problem can be caused by a number of different faults. One fault finding thing that seems to be omitted on occasions is when it is re-gassed, they need to put in a UV dye so that any slow leaks can be detected.
 
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