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Correct A/C operation

Posted: Tue Jul 19, 2022 11:26 pm
by mrlimit
Hi Guys, a little while since I posted but have a question that hopefully someone can answer?

I replaced my A/C condensor last year & had the truck re-gassed to spec, all seemed ok when I picked her up (A/C seemed to be blowing cool) etc etc. Fast forward to this summer & things have been heating up here in the UK, so have obviosly been using the A/C a lot, however i have noticed that the air coming from the vents seems to alternate between cold and well.. not so cold!
Don't get me wrong, it does seem to cool down the truck (eventually) but I don't remember it doing this before I changed the condensor and had a re-gas.
The cycle of cold/not so cold air coinsides with the A/C compressor cycling on/off ( 3 or 4 times a min.)

My question is: should the A/C compressor cycle on & off during normal operation, or is this a sign of a problem?
Forscan shows no faults & I have monitored the HVAC low pressure switch status, which never changes. Are there any other sensors i can look at via forscan to try and diagnose a potential problem, or is this just computer wizardry tellin the A/C compressor to switch on/off?
Truck is 2016 3.2 limited.

Cheers, Clayton.

Re: Correct A/C operation

Posted: Wed Jul 20, 2022 10:04 am
by RossPat
If I drive on a 38 - 42+ degree day my aircon rarely cycles
4 door Ranger has a big area with a lot of glass to cool off
Plus I have mine set on the coldest setting.
If I have it going in temps of 30d it does cycle but not that often, maybe every 10 mins

Re: Correct A/C operation

Posted: Wed Jul 20, 2022 1:02 pm
by CatHerder
mrlimit wrote: Tue Jul 19, 2022 11:26 pm.... the air coming from the vents seems to alternate between cold and well.. not so cold!
Clayton,
Traditionally, I'd see that as the AC system has been overcharged with refrigerant and the evaporator [cyclically] icing up.
Maybe the high temps in ol' blighty this week have increased the AC's internal pressure above what it's used to and it's misbehaving?.

Re: Correct A/C operation

Posted: Wed Jul 20, 2022 5:46 pm
by mrlimit
Hi Chaps, thanks for the answers. I did wonder if it was an over pressure problem. Is there any way to confirm this with forscan, or do I need to get a set of pressure gauges on it?

Re: Correct A/C operation

Posted: Thu Jul 21, 2022 6:31 pm
by mrlimit
So, quick update. Had a word with ford and got the exact quantity of refregerant that should be used (565g) Got my local shop to empty & then re-fill to this exact amount. Drove the truck and A/C still behaving the same way!
So at the moment it's not looking like an overcharge problem. Any idea's what else it could be??

Re: Correct A/C operation

Posted: Fri Aug 05, 2022 12:00 am
by mrlimit
So, final update. It would appear that what I am experiencing is "normal operation" after all. I sat & watched the evap temp using Forscan & when the temp dropped down to 36F or lower, the A/C clutch would drop out, when the evap temp got back up to 37F the clutch would drop in again. So basically the evaperator temp is being kept just above freezing all the time. the only thing that altered the A/C in / out frequency was putting the blower on Full chat, it then took longer for the A/C clutch to cycle. So, i guess this is normal after all!

Re: Correct A/C operation

Posted: Sat Aug 20, 2022 3:24 pm
by saeb
Good to know and you learnt something and shared the story, thank you.