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Hi,
Does the amount of air flow out the vents diminish during this time period?
The evaporator might be icing up in this scenario.
If this car uses an orifice expansion device it can be caused by an unbalanced refrigerant charge.
In most cases it has lost just enough gas that the evaporator cannot hold enough charge on the low side to keep the coil above freezing.
Try reading this as it explains the workings well.
https://technician.academy/what-does-an-orifice-tube-do-in-an-ac-system/
A history, as I see it, in my own opinionated way. 🤫
It could be just a low charge but it’s not as simple as the old days with sight glasses made it possible to see the filled up level, that actually had a built in reserve.
It’s the reserve that worried manufacturing bean counters some.
BUT the environmental groups got heard about ozone to everyone’s chagrin, if you check it out.
Now the harp is on R134A’s carbon dioxide foot print.
Jeez?
BUT …. R 1234YF is flammable, Yell Fire abbreviated right on the can.
EPA got it wrong again and Mercedes was first to complain.
BUT … America buys and destroys lots of cars YEARLY.
These system in the link above showed up in the early nineties on the 240s because of the change over to R134A from R12.
Using less expensive components was to supposedly compensate for bringing on more engineering costs by not using an established a TXV design.
Refrigerators have always used cheaper long capillary tubes.
It’s a fixed orifice mechanism with no moving parts too.
It uses a critical charge but of only a few ounces.
Total different heat loads and has time to cool. Tiny compressors but they have to run more hours and wear out. Hello.
The R134 was less efficient by 10% so things had to be made larger to compensate.
The 240s got more blower volume, a fan unit on condensers outside even though they stayed with the same size. There’s another engineering clunk in that scenario.
All this prolong the death of 240 but it sorely needed an upgrade anyway.
Some say it’s still wasn’t enough ?
Sweden is northern and mountainous so air conditioning wasn’t necessary there so not a priority.
Volvo always borrowed or bought designs during those years as they came to the states.
The dealers here were adding on A/C units. My 1978 has one with that split pulley. Another story.
The gas embargo and America building lousy vehicles caused Volvo, Europe and Japan to have growing pains to help us down size.
In order to meet consumer demands and changes Volvo started to those ideas had to change.
Along came the threat of FWD that Volvo said they would never build for SAFETY!
HA, That line was tired too!
Now this electric thing, WHAT is that doing to Volvo and others?
So there went the simplistic but solid 240s and on with the experimental body styles.
The 700, 900 and 850 smushed into a time line along with their own tribulations.
Bigger American cars had room for gigantic AC systems.
Americans and its marketing loves A/C tweaks and other gadgets. Those have grown on us like unexpected warts. 😬
Do we really need all this complexity?
Climate controlled zones inside a shared cabin?
Be thankful it’s cooler at all. IMHO
The proper way to recharge this system is remove all the refrigerant, weigh it and put back in with the correct charge total.
But in the interim of that, get the leak, as it surely has one, repaired.
If this is the original charge it might be from long term permeation from the rubber HOSES.
That’s one of a few faulty parts of automotive system. The vehicle need flex where refrigerator boxes do not.
PLUS the auto compressor is Mechanical and not hermetically sealed.
Phil
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