diff --git a/game/reconstructed/heatfamily_reslice.cpp b/game/reconstructed/heatfamily_reslice.cpp
index 42dca35..c67f899 100644
--- a/game/reconstructed/heatfamily_reslice.cpp
+++ b/game/reconstructed/heatfamily_reslice.cpp
@@ -977,6 +977,22 @@ void BTRecomputeCondenserValves(Entity *owner)
 	Derivation &condClass = *Condenser::GetClassDerivations();
 	int count = owner->GetSubsystemCount();
 
+	// DIAG (BT_VALVE=<n>): force every condenser's valve detent so the coolant/jam
+	// mechanic can be tested at a known coolant level (0=closed/uncooled .. 50=max).
+	{
+		const char *fv = getenv("BT_VALVE");
+		if (fv && fv[0])
+		{
+			int v = atoi(fv);
+			for (int i = 0; i < count; ++i)
+			{
+				Subsystem *s = owner->GetSubsystem(i);
+				if (s != 0 && s->IsDerivedFrom(condClass))
+					((Condenser *)s)->valveState = v;
+			}
+		}
+	}
+
 	// pass 1: total valve opening across all condensers
 	int total = 0;
 	for (int i = 0; i < count; ++i)
diff --git a/game/reconstructed/projweap.cpp b/game/reconstructed/projweap.cpp
index 9df8bfc..032adeb 100644
--- a/game/reconstructed/projweap.cpp
+++ b/game/reconstructed/projweap.cpp
@@ -517,6 +517,16 @@ void
 Logical
 	ProjectileWeapon::CheckForJam()
 {
+	if (getenv("BT_JAM_LOG"))
+		DEBUG_STREAM << "[jam] " << GetName()
+			<< " T=" << currentTemperature
+			<< " degT=" << degradationTemperature
+			<< " failT=" << failureTemperature
+			<< " alarm=" << (int)heatAlarm.GetLevel()
+			<< " liveFire=" << (int)LiveFireEnabled()
+			<< " p=" << ((_DAT_004bc064 * currentTemperature) / failureTemperature)
+			<< "\n" << std::flush;
+
 	if (!LiveFireEnabled())										// *(*(this+0xd0)+400)+0x25c
 		return False;