Chattering LLS on small WIF

[vettehead]

I ran across a small WIF that was only able to get to 20F. Tstat was calling so LLS was open and unit running. Once I got back to the roof the liquid line was making all this chatter. I ran back downstairs to discover the noise coming from the LLS valve. While energized the coil chattered like heck, stop for a while, then chatter a lil more then stop, etc . Customer said the chattering noise has been happening for sometime off and on.

Can those plungers get 'stuck' inside the valve? (This unit has had multiple surgeries) OR...Is there such a thing as a weak coil? Yes proper voltage was delivered to coil.

AND to further complicate matters...I was only able to get a 185 psi HS / 20 psi LS w condenser papered off completely. (R-22). I suspect this outdoor unit of a failing Alco headmaster as ambient was around 60F. and refrigerant seemed like it was entering the conderser and noy bypassing. But if a LLS is not openng completely this may explain the low pressure conditions . Sight glass was solid. My head hurts.

[powerup]

I ran across a small WIF that was only able to get to 20F. Tstat was calling so LLS was open and unit running. Once I got back to the roof the liquid line was making all this chatter. I ran back downstairs to discover the noise coming from the LLS valve. While energized the coil chattered like heck, stop for a while, then chatter a lil more then stop, etc . Customer said the chattering noise has been happening for sometime off and on.

Can those plungers get 'stuck' inside the valve? (This unit has had multiple surgeries) OR...Is there such a thing as a weak coil? Yes proper voltage was delivered to coil.

AND to further complicate matters...I was only able to get a 185 psi HS / 20 psi LS w condenser papered off completely. (R-22). I suspect this outdoor unit of a failing Alco headmaster as ambient was around 60F. and refrigerant seemed like it was entering the conderser and noy bypassing. But if a LLS is not openng completely this may explain the low pressure conditions . Sight glass was solid. My head hurts.

I would look for a shorting LLS wire then try another coil and if that did'nt do I 'd install new solenoid valve and coil. Good luck and let us know how it works out. And yes to your question coils can change resistance and often do.

[Leo3006]

Pump down and remove the guts from the LLS and see if it changes the pressures with cond blocked. LLS/TXV's requires certain Pressure delta T to operant properly. Is there a filter/dryer on the system? Delta T?

With condenser blocked off, I would think you would see a higher head???? Do you have a pinch off tool? Pinch off the Head master to take it out of the circuit. You can open the pinch off with a flaring tool block.

I check this blog rarely anymore due to the idiots on it. Good luck.

PS, I wonder what the pressures were doing while the chattering was going on? Broke valve on compressor? pump down?

I know, no great help, but things to think about.;

[vettehead]

Thanks Leo. I always thought the LLS opened and closed on coil voltage. Period. Either open or closed...no grey area. Are you saying if the pressure on the 'front' side of the LLS is too low, the valve may chatter..? If that's the case then I may have to look closer at perhaps a faulty headmaster causing a low LL pressure. Pinch off is possible but it wasn't too cold today
(60-65 F ambient) Usually headmasters come into play when it's much colder out. I blocked off condenser 100% and was only able to see HP go up 25 psi to 185 or so. Previous post suggested changing solenoid coil (it's so damn simple) as a shorted coil could prevent complete opening.

I thank both for the suggestions and I will follow up with my results

[rayr]

No one suggested checking the input voltage first?????

[local 832s]

He said proper voltage is being delivered

[local 832s]

Does the valve have a manual stem?

[r404a]

I second the notion of checking for a short somewhere. May not neccesarily be a short to the wiring to the coil itself, just somewhere in the system that could be dragging power down instantaneously. Leo is right about differential, but 185 head should get it. Think about curving the compressor at this point due to not being able to elevate head.


r404a

[rayr]

He said proper voltage is being delivered

OOOOOPPPPSSSS. My bad...Sorry

[calgarycool]

I would be looking to open the LLS on a manual stem if possible. If you know the valve is feeding constantly you can rule out other system problems. If the system runs normally after this, then I would start looking for a poor electrical connection to the solenoid valve.

[sarpanch2001]

Using R-22 on WIF ? are u working on supermarket ? I would say check capacity for LLSV if it bigger then capacity you see same problem what you have check coil voltage. is it right for coil ?i mean you are not feeding 230v coil 115 V also check 115 from each leg to ground if 230 v

[local 832s]

Does the valve have a manual stem?

???

[vettehead]

I dont think I have an issue with the LLS at all. Here is what I found. I'm still confused

It's a Russell 1 HP split system, R-22, 208/230/1. (MLH100L44) At first I was looking for a refrigeration type problem as I was only able to get 15 *F box temp . Then I noticed an odd occurance when it goes into defrost, the liquid line solenoid should de-energize, def. heater comes ON, and pump down should occur. However, this unit turns the heaters ON <fine> but the LL solenoid coil starts chattering and compressor never shuts OFF on pump down. Chattering is sporadic but very noticeable during this defrost cycle. So the heater is fighting the cooling cycle. The timer is a very old 8145-20 Paragon with X terminal termination or time termination.

As I watched this "fighting" of the defrost cycle and the cooling cycle, I disconnected the #4 wire feeding the LLS. Pumpdown then occurred and the compressor went OFF. Alleluia! The htrs. stayed ON until termination switch on evap coil opened and heaters shut OFF. I thought this would trigger timer X terminal to restart cooling cycle but nothing happened. Remember I still have the #4 disconnected. A re-coonect of the #4 wire and refrigeration would start again but the problem is not solved

A continuity check of the timer showed no continuity between #1(line) and 3 (def) and 4 (cool) simultaneously when I advanced the clock into defrost. I'm wondering if the LLS is getting one leg (115v) causing the chattering and perhaps on partially opened LLS preventing pump down from occuring. (No I didn't measure coil voltage while defrost was initiated...will do tommorow)

I'm so tempted to change the old clock but I hate to change something without knowing for sure...and would really like to understand what the heck is going on.