99 S70 - It's summer annnnnd my AC isn't cold anymore

[Auburn T5]

I recharged the coolant last year and that did the trick. this time, no such luck. It wasn't a swift death of the cool air though, it gradually faded over the last month.

Here is what is weird. It is still sort of cool if the ambient outside temperature is in the 70's or 80's *F but last week, it was in the low 90's and it was just nothing but hot air coming out of the vents. I had the slider all the way up and both temp dials all the way down at the blue dots and no luck.

With the AC controls still set like that, while parked/idle, the compressor engages for almost exactly 3 or 4 seconds then turns off for 3 or 4 seconds over and over again.

My compressor was shimmed (metal not plastic bread clips) a few years ago.


I'm doing some research here before taking it to a mechanic as I would prefer to DIY and save myself some money but if it ends up being the evaporator, I may pay my mechanic to tackle that one (and fix my cracking/squeaking dash)

Anyways, I read that I need to have someone holding the RPM's at 1500~ish when checking the freon pressure. Maybe it does just need recharging again and I didn't have the rpm's where they needed to be?

What other possible things can I check myself?

Thanks for any info!

[jblackburn]

Clicking on and off every 3 seconds means it needs recharging - recharging at idle often won't completely fill it up. Every time it clicks off, the low-side pressure has fallen to 25 PSI and the compressor cuts out to save itself from damage.

Most cans of refrigerant have a R-134a pressure chart on the back of them - shoot for the low end of the scale according to your ambient temp and hold the idle at 1500.

[Auburn T5]

thanks I'll give that a try tonight.

[JRL]

Evaporator is failing like each and every one of these do
Fill and see how long it lasts. You may be lucky and get one more season out of it
If you get down to filling each month, it's time for a new evaporator

[Auburn T5]

Evaporator is failing like each and every one of these do
Fill and see how long it lasts. You may be lucky and get one more season out of it
If you get down to filling each month, it's time for a new evaporator

That's my biggest fear although it would mean that I wouldn't have a squeaking dash any more which is incredibly annoying.

[abscate]

Has anyone used a fiber scope to confirm a bad evap by looking through the blower fan mount?

[Auburn T5]

Has anyone used a fiber scope to confirm a bad evap by looking through the blower fan mount?

No this is just an initial quick/cheap fix solution I'm after if possible.

Anyways, an update: emptied an entire can of refrigerant into the port while my wife held the RPM's at around 1500 and the compressor is still cycling on/off with fairly short and regular intervals and the air is not cold. It's not ambient temp but it's not cold either.

AC line running into the firewall is cold though. I'm fearing the worst here...

[abscate]

Have you measured the compressor clutch gap? Worth checking.

If a can last less than a month then you need to fix the leaky component(s) to prevent major moisture damage to the really expensive stuff like the compressor

[jblackburn]

My car took 2 small cans when it was almost completely empty.

Sounds like it's time for an evaporator soon if it won't hold for long...

[AVIP]

Mine had a tonnn of ac issues. A mechanic added the uv dye to make it easier:)