Search found 9 matches

by thp
Wed Jul 03, 2019 1:38 am
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Re: Evap freezing at low fan speeds

Yes, in fact I was concerned about the cycling. There's a lot of material out there suggesting that rapid cycling is problematic in itself, and symptomatic of larger issues.

But if your experience tells you it's normal, that's good news for me. Thanks for the help.
by thp
Mon Jul 01, 2019 10:26 pm
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Re: Evap freezing at low fan speeds

Rapid cycling can happen with any CCOT system


It's not an orifice tube system--it's got TXVs.

The rapid cycling is still expected? I checked again and it's cycling every six seconds or so. Seems like an awful lot.
by thp
Mon Jul 01, 2019 4:40 pm
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Re: Evap freezing at low fan speeds

Item 16 is the solenoid valve. Yes, it's present, but I suppose I haven't checked to see if it's actually closing or not. I can look at the differential temperature across the valve to see if it's operating. This is something I was thinking about the other day. About cycling: Cycling on and off ever...
by thp
Sun Jun 30, 2019 4:56 pm
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Re: Evap freezing at low fan speeds

Thanks for the responses guys. @JohnHere: Yeah, pulled plenty good vacuum--below 300 micron for an hour. Holds there for ages, so no leaks. @Cusser: No, I added by weight from a 30lb cylinder of genuine DuPont Suva R134a. I pulled a vacuum in the manifold gage and lines before opening the cylinder i...
by thp
Mon Jun 24, 2019 5:03 am
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Re: Evap freezing at low fan speeds

The evaporator switch is a capillary type. It gets inserted into a hole in the side of the evap core, which I assume lines up with a tube in the side of the evap itself. I don't think there's any mistake possible there, and the temp is definitely getting down to freezing. One idea is to retrofit a t...
by thp
Tue Jun 11, 2019 11:45 pm
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Re: Evap freezing at low fan speeds

Yes, US vehicle. And yes the system was originally fit with a Sanden SD7H15 as you show. A number of online parts houses show the Denso as being compatible, but who knows. I didn't buy it from a specialty AC parts shop (I didn't know about shops like this at the time...) and this is a subtle issue s...
by thp
Tue Jun 11, 2019 2:42 pm
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Re: Evap freezing at low fan speeds

This system is not meant to cycle. The service manual claims the compressor has an internal pressure regulator, which I assumed was an internal control valve? I haven't looked closely at the compressor recently, but I seem to remember a circular nubbin that looks like one. I'm not running a Sanden, ...
by thp
Mon Jun 10, 2019 9:22 pm
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Re: Evap freezing at low fan speeds

The charge is dead on. I verified a couple times, including when I changed the TXV. What part looks wacky? I would think the changes from turning on or off the rear AC are expected. When it's on a solenoid opens and you get the pressure drop across the rear TXV and evap added in parallel to the fron...
by thp
Sun Jun 09, 2019 12:00 pm
Forum: Automotive Air Conditioning Forum
Topic: Evap freezing at low fan speeds
Replies: 20
Views: 2723

Evap freezing at low fan speeds

Year: 1993 Make: VW Model: Eurovan Engine Size: 2.5, front and rear AC Refrigerant Type: R-134A Ambient Temp: 80F System cools great. However the compressor cycles every ~10 seconds on front evaporator anti-ice switch when blower is set below full blast. Basically the low side drops too low when the...

Go to advanced search