SB 400 specialist

[madcash2]

Hi all

I'm looking to get in touch with a specialist who knows the SB 400 well. Please

[cadwaladr]

What do you need to know?

[madcash2]

I have a unit that I'm working on that doesn't seem to be cooling efficiently. There is enough refrigerant as I fully charged it by weight 19lbs. R404a. How familiar are you withered units....

[cadwaladr]

Quite familiar,have you got any readings, pressures, temperatures,what is the ambient temperature where you are operating?

[cadwaladr]

Looking at the ambient in your location you must keep the condensor clean,by rinsing it with none corrosive cleanser on a regular basis.

[madcash2]

So basically yesterday after am all night evacuation I recharged unit. Ambient was reading 40ºc on the display. Box was about 30 when I started the unit. Low side about 50 and high side about 380/390. Box temp eventually came down to 0ºc after about 4 hours. High side 340 psi low side about 30 psi. Ball in site glass not at the top but half way up and floating in liquid. Thing is with an empty box it should drop to Zero much faster than that when I compare with another unit I have. There is just something not right. At 0ºc the main suction line was frosted up and the economise line slightly cool. Today I want to check the ETV because u did a service test for that and it failed.

[cadwaladr]

Have you checked the evaporator is not blocked with debris,which would affect airflow and has the condensor been cleaned.

[madcash2]

Yes it's fine. Today after further testing the unit seems to be under heavy load and can not even run at full RPM in HSC. So did more digging and I suspect a faulted loader valve. LV1 I have change it and will test again on Monday. When the unit is run in HSC.U/P it runs fine. The faulty LV1 would coinside with economiser suction line being warm as well. So let's hope this sorts out the problem.furthermore when is did the relay board test in lv 1/2. #2 had two clicks #1 only one click now that I have changed it can hear two clicks on both. So hopefully it was stuck in one position.

[mbc]

hi
something wrong on high side
340 psi is too much for 40

also check short gas

[madcash2]

Short gas? I recharge by weight

[madcash2]

Is it possible to upload an extract from the service manual?

[madcash2]

Yes it's fine. Today after further testing the unit seems to be under heavy load and can not even run at full RPM in HSC. So did more digging and I suspect a faulted loader valve. LV1 I have change it and will test again on Monday. When the unit is run in HSC.U/P it runs fine. The faulty LV1 would coinside with economiser suction line being warm as well. So let's hope this sorts out the problem.furthermore when is did the relay board test in lv 1/2. #2 had two clicks #1 only one click now that I have changed it can hear two clicks on both. So hopefully it was stuck in one position.

please note i have improved performance how ever i'm still not happy fully with the performance. Pressures seem ok but ball is down, please see the attached data sheet of all the service test modes i carried out. 14427

https://www.dropbox.com/s/v2vcdbk5i9cy565/SB-400%20chart.pdf?dl=0

the link has the parts of the manual i used to try and diagnose the problem at this point i'm suspecting the heat check valve after reviewing the symptoms chart. Please tell me your views before i loose the refrigerant.

[madcash2]

Any one have a solution.?