Blower fan goes on and off every few seconds

Hello World!

I'd greatly appreciate some help here.

I've a 10+ years old National (now known as Panasonic) air conditioner, CS-C9CKN. Only used a few times every year when it's extremely hot.

Recently, it started to go on and off every few seconds. I got a professional to investigate the problem and he suspected the PCB is faulty. We've narrowed down the problem to the fan or components related to it because it still happens in Fan mode. I've searched around and found out that most troubleshooting in my region are trial and error (try changing component A, then component B, and so on), so I guess my contractor was honest to ask me to change the blower. Blower+Labor is 1/3rd the price of a new complete unit. PCB+Labor could be slightly cheaper but he does not have the spare part.

Since it's "dead", I took out the PCB and it appears ok. No bloated capacitors or burnt components but I still try to change the caps anyway. Made no difference. In process of soldering, I think one of roundish metallic ring (to make it easier to solder a cap, I think) for a cap on the PCB came off, and Fan mode no longer blow air. The blower remains on though. If I switch to Cooling mode, cold air (fan works here) comes out and the on-off symptom goes on. So I did further research on the net and found out that it could be the fan or fan motor.

The condenser unit works fine. I can feel the fan is blowing and it's cold probably because the blower is not sending out hot air.

Before I start dismantling the evaporator to inspect the fan, I thought of getting some opinions here. What else could be causing this?

Thanks in advance.

 

Welcome to the forums.

If your fan is turning on and off every few seconds then the problem is NOT the fan. It's what controls the fan. In this case of a split unit..... the problem is most likely the control board inside the house part of the system.

A visual inspection of an electronic control board means very little. If the unit was dead you might see something burned. Since it's intermittent.... you won't see the problem.

 

I would contact tech support with a minisplit giving those symptoms.

 

Thank you so much for the warm welcome, PJmax. And thank you very much PJmax & Houston204 for your responses.

I'll try to source and borrow a similar one to test out.

I can try out their tech support, but unsure how much they'll entertain for free. Their dealer did say it's old and unlikely they have parts. Repair costs are probably high.

 

I managed to convince a friend to lend me his controller board. Same problem.

Any chance that the problem lies with the condenser unit? If it isn't, I'll try dismantle the evaporator and check out the fan and fan motor. Just to recap, this problem happens even in fan mode without cooling.

Or anything else to try to narrow down the problem?

Thanks

 

The inside unit is the brains for the system and tells the condensor when to turn on. If the condensor is not running then the problem is not out there.

I'm going to try to locate the service manual for the unit.

 

Thanks Pete.

I should've posted that along. I got it from PANASONIC CS-C7CKP SERVICE MANUAL Pdf Download.. Click on the green Download button at the upper left.

 

Did I read that correctly you soldered new caps into the control board???? your original problem could have been as simple as a loose wire connection on your tsat wiring? (typically the green wire)

 

Thanks for stepping in, Former Member.

Well, I got it inspected by an Air Cond technician prior to that. I don't fancy dismantling things I'm not familiar with. But his advice was to change the blower unit. That's when I started dismantling it. Never had much luck with electronics apart from bloated caps visible to the eye, so I avoid this as much as I could until I got it inspected by a qualified technician.

Anyway, I just checked the wires, they're appear intact in front. Might have to check the other end that goes to the fan/tsat. That requires further dismantling.

 

Given to the air conditioner installer to be disposed as scrap metal (as so they claimed).

Wires seem ok to me, nothing loose. Couldn't dismantle the fan motor on the blower unit and didn't want to spend big bucks to get a motor.