# TXV Freezing Diagnostic

**Date:** 2026-07-04
**Saved by:** Mustafa (GHQMaster) -> Nexus vault

## Scenario
TXV body itself is freezing on an HVAC/R system.

## Diagnostic Flow
1. If TXV is iced solid -> lost bulb charge OR clogged inlet screen/strainer
2. Feel TXV inlet vs outlet while running:
   - Inlet warm, outlet freezing -> restriction (clogged strainer/filter)
   - Both freezing -> valve starving coil (lost bulb charge)

## Root Causes
- Lost bulb charge - sensing bulb leaked refrigerant, valve stays closed, massive pressure drop chills valve body. Most common.
- Clogged inlet screen/strainer - partial blockage after compressor burnout or no filter-drier change.

## Fix
1. Recover refrigerant
2. Cut out TXV
3. Replace filter-drier
4. Blow out line set with nitrogen
5. Install new TXV (do not reuse)
6. Evacuate
7. Recharge

## Context
Baber asked about using candle heat on a TXV to diagnose a stuck valve. Not recommended - hand warmth is safer and equally diagnostic. A candle wont fix a mechanical failure.

## Tags
hvac, refrigeration, txv, troubleshooting, hvac-r